Explosions were heard Friday morning in the Iranian capital, state TV reported, adding that Iran's air defence were at "100 percent operational capacity".

Israel declared a state of emergency, with Defence Minister Israel Katz saying that retaliatory action from Tehran was possible following the operation.

"Following the State of Israel's preemptive strike against Iran, a missile and drone attack against the State of Israel and its civilian population is expected in the immediate future," Katz said.

Oil prices surged as much as 6 percent on the strikes, which came after Trump warned of a possible Iranian attack and said the US was drawing down staff in the region.

"I don't want to say imminent, but it looks like it's something that could very well happen," Trump told reporters at the White House Thursday when asked if an Israeli attack loomed.

Trump said he believed a "pretty good" deal on Iran's nuclear programme was "fairly close", but said that an Israeli attack on its arch foe could wreck the chances of an agreement.

The US leader did not disclose the details of a conversation on Monday with Israeli Prime Minister Benjamin Netanyahu, but said: "I don't want them going in, because I think it would blow it."

Trump quickly added: "Might help it actually, but it also could blow it."

A US official said there had been no US involvement in the Israeli strikes on Iran.

-- 'Extremist' --

The United States on Wednesday said it was reducing embassy staff in Iraq -- long a zone of proxy conflict with Iran.

Israel, which counts on US military and diplomatic support, sees the cleric-run state in Tehran as an existential threat and hit Iranian air defences last year.

Netanyahu has vowed less restraint since the unprecedented October 7, 2023 attack on Israel by Tehran-backed Hamas, which triggered the massive Israeli offensive in Gaza.

The United States and other Western countries, along with Israel, have repeatedly accused Iran of seeking a nuclear weapon, which it has repeatedly denied.

Israel again called for global action after the UN's International Atomic Energy Agency (IAEA) accused Iran on Wednesday of non-compliance with its obligations.

The resolution could lay the groundwork for European countries to invoke a "snapback" mechanism, which expires in October, that would reinstate UN sanctions eased under a 2015 nuclear deal negotiated by then US president Barack Obama.

Trump pulled out of the deal in his first term and slapped Iran with sweeping sanctions.

Iran's nuclear chief, Mohammad Eslami, slammed the resolution as "extremist" and blamed Israeli influence.

In response to the resolution, Iran said it would launch a new enrichment centre in a secure location.

Iran would also replace "all of these first-generation machines with sixth-generation advanced machines" at the Fordo uranium enrichment plant, said Behrouz Kamalvandi, spokesman of the Atomic Energy Organization of Iran.

Iran currently enriches uranium to 60 percent, far above the 3.67-percent limit set in the 2015 deal and close, though still short, of the 90 percent needed for a nuclear warhead.