JERUSALEM — The Iranian foreign minister, Mohammad Javad Zarif, vowed revenge against Israel on Monday morning, a day after a blackout at an Iranian nuclear enrichment site was attributed to an Israeli attack.
Mr. Zarif’s comments highlight the risk of escalation in a yearslong shadow war between Iran and Israel. They also threaten to overshadow efforts in Vienna to encourage Iran to reimpose limits on its nuclear program in exchange for the lifting of American sanctions.
In a statement broadcast by Iranian state television, Mr. Zarif was quoted as saying: “The Zionists want to take revenge because of our progress in the way to lift sanctions.”
He added, “But we will take our revenge from the Zionists,” according to the broadcast.
Mr. Zarif’s reported comments followed a power failure on Sunday at the Natanz uranium enrichment site that Iranian officials attributed to Israeli sabotage. The Israeli government declined to comment on its involvement, but American and Israeli officials confirmed separately to The New York Times that Israel had played a role.
Israeli news outlets, citing intelligence sources, attributed the attack to the Mossad, the Israeli spy agency.
Two officials briefed on the matter told The Times that the blackout was caused by an explosion that targeted the power supply for thousands of underground centrifuges that form the main Iranian enrichment program.
A spokesman for the Atomic Energy Organization of Iran, Behrouz Kamalvandi, said on Monday that the blast had created a crater so big that he had fallen into it, injuring his head, back, leg and arm.
The attack risked igniting public tensions between Israel and the Biden administration over the right way to approach Iran and its nuclear ambitions. It occurred as the U.S. defense secretary, Lloyd J. Austin III, was in Israel for meetings with Prime Minister Benjamin Netanyahu and Defense Minister Benny Gantz.
Israeli and American officials declined to say whether the U.S. government had been warned of the attack in advance, or whether the attack had been timed to coincide with Mr. Austin’s visit.
A White House spokesman said Monday that “the U.S. was not involved in any manner and we have nothing to add to speculation about the causes.”
The official, speaking on condition of anonymity, did not comment on whether the United States had been given advance notice of the attack.
Both Mr. Austin and Mr. Netanyahu projected an image of friendship on Monday afternoon at a joint press briefing. In brief statements, Mr. Austin did not mention Iran at all, while Mr. Netanyahu referred only obliquely to the attack on Sunday.
Iran has long maintained that its nuclear program is peaceful and aimed at energy development. But Israel sees it as an existential threat, since Iranian leaders have often called for Israel’s destruction.
“We both agree that Iran must never possess nuclear weapons,” Mr. Netanyahu said Monday. “My policy as prime minister of Israel is clear. I will never allow Iran to obtain the nuclear capability to carry out its genocidal goal of eliminating Israel, and Israel will continue to defend itself against Iran’s aggression, and terrorism.”
Mr. Netanyahu described the United States on Monday as “not just allies — we’re family.” But the Natanz attack was a reminder of the differences between Mr. Netanyahu’s Iran policy and President Joseph R. Biden’s approach.
The episode could complicate efforts by the Biden administration to encourage Iran to return to something close to the 2015 agreement negotiated by the Obama administration, in which Tehran promised to limit its enrichment program in exchange for sanctions relief.
The deal collapsed in 2018, when President Donald J. Trump reimposed sanctions on Iran, and Iran later abandoned commitments to curb its nuclear plans.
Israel opposes returning to the same deal, arguing that it did not impose strong enough or long enough restrictions on Iranian nuclear activity.
A senior official in the prime minister’s office declined to say what Mr. Austin and Mr. Netanyahu discussed in their private meeting. A second Israeli official said that Mr. Austin and Mr. Gantz discussed Israel’s opposition to returning to the same deal agreed in 2015, but declined to say whether the men discussed the Natanz attack.
Analysts were divided about whether Israel’s aggression was intended to scupper the negotiations altogether — or to simply weaken Iran’s hand at the table.
The German foreign minister, Heiko Maas, said that the blackout did not augur well for the negotiations in Vienna. “What we are hearing currently out of Tehran is not a positive contribution, particularly the development in Natanz,” he said Monday.
For years, Israel and Iran have been engaged in a low-level shadow conflict.
Both have been accused of cyberattacks on the other’s territory. Iran finances and arms militias hostile to Israel across the Middle East, and has been accused of attempted assassinations of Israeli diplomats across the world. Israel is believed to be responsible for the assassination of several Iranian nuclear scientists, most recently in November, when a leading architect of the Iranian nuclear program was killed in an ambush.
Those attacks have escalated at sea in the past two years, as Israel began to attack ships carrying Iranian fuel, and Iran seemed to respond by targeting at least two Israeli-owned cargo ships.
Both sides managed to contain the conflict, partly by refraining from speaking too publicly about the attacks.
But the leaking of details about Israeli involvement in Sunday’s episode raised fears that Iran would seek to save face by mounting a stronger military response than usual.
“Once Israeli officials are quoted, it requires the Iranians to take revenge,” Danny Yatom, a former head of the Mossad, said in an interview Monday with a radio station run by the Israeli Army. “There are actions that must remain in the dark,” he added.
In the days before the attack, Israel asked the United States for assistance in protecting an Israeli-owned cargo ship that is currently in the Arabian Sea, an American official said.
Israeli officials expressed concern that the ship, the Hyperion Ray, could be targeted by Iran’s Islamic Revolutionary Guards Corps following last week’s apparent mine attack by Israel on an Iranian military vessel in the Red Sea, the U.S. official said. The Israeli government declined to comment.
A ship owned by the same Israeli company, the Helios Ray, was attacked in February, and Israel blamed Iran.
But some analysts expected that Iran would be unwilling to escalate further while there was still a chance that America might pare back sanctions on the Iranian economy in exchange for Iran’s scaling back its nuclear program.
Chuck Freilich, a former deputy national security adviser in Israel, said: “I don’t think the Iranians want a major confrontation at this point — I think they want a deal. And that doesn’t need a confrontation.”
In Israel, some also questioned whether the attack served a domestic purpose for Mr. Netanyahu, rather than just a foreign policy objective.
Mr. Netanyahu is standing trial for corruption and is struggling to form a new coalition government after a general election last month that gave no party an overall majority. Some analysts say they believe that a very public confrontation with Iran might help Mr. Netanyahu persuade wavering coalition partners that now is not the time to remove an experienced prime minister.
“He may want to both build up his image and create a little bit of a foreign policy crisis, which then helps him solve the coalition crisis,” Mr. Freilich said.
Reporting was contributed by Myra Noveck in Jerusalem, Steven Erlanger in Brussels, Eric Schmitt in Washington and Farnaz Fassihi in New York.