The attack's limited scale on Friday and Iran's muted response appeared to signal a successful effort by diplomats working to avert all-out war since an Iranian drone and missile attack on Israel on Saturday.

Iranian media and officials described a small number of explosions, which they said resulted from Iran's air defences hitting three drones over the city of Isfahan.

Notably, they referred to the incident as an attack by "infiltrators", rather than by Israel, obviating the need for retaliation.

An Iranian official told Reuters there were no plans to respond against Israel for the incident.

"The foreign source of the incident has not been confirmed. We have not received any external attack, and the discussion leans more towards infiltration than attack," the official said.

Israel said nothing about the incident.

It had said for days it would retaliate against Iran for Saturday's strikes, the first-ever direct attack on Israel by Iran in decades of shadow war waged by proxies that has escalated during six months of battle in Gaza.

The longstanding foes had been heading towards direct confrontation since a presumed Israeli air strike on April 1 that destroyed a building in Iran's embassy compound in Damascus and killed several Iranian officers.

Iran's response, with a direct attack on Israel, was unprecedented but caused no deaths and only minor damage because Israel and its allies shot down hundreds of missiles and drones.

Allies including the United States had pressed hard to ensure any further retaliation would not provoke a spiral of hostilities.

The British and German foreign ministers visited Jerusalem this week, and Western countries tightened sanctions on Iran to mollify Israel.

In a sign of pressure within Israel's hard-right government for a stronger response, Itamar Ben Gvir, the far-right national security minister, tweeted a single word after Friday's strikes: "Feeble!"

Countries around the world called on Friday for both sides to avert further escalation.

"In light of reports of strikes on April 19th, we urge all parties to work to prevent further escalation," foreign ministers of the Group of Seven industrialised democracies said in a statement at the end of a three-day meeting in Italy.

Within Iran, news reports on Friday's incident made no mention of Israel, and state television carried analysts and pundits who appeared dismissive about the scale.

An analyst told state TV that mini-drones flown by "infiltrators from inside Iran" had been shot down by air defences in Isfahan.

Shortly after midnight, "three drones were observed in the sky over Isfahan. The air defence system became active and destroyed these drones in the sky," Iranian state TV said.

Senior army commander Siavosh Mihandoust told state TV that air defence systems had targeted a "suspicious object".

The International Atomic Energy Agency confirmed there was no damage to Iran's nuclear sites and called for extreme restraint from all sides.

The Natanz nuclear site, the centrepiece of Iran's uranium enrichment program, is in Isfahan province.

Iranian President Ebrahim Raisi had warned Israel before Friday's strike that Tehran would deliver a "severe response" to any attack on its territory.

Iran told the United Nations Security Council on Thursday that Israel "must be compelled to stop any further military adventurism against our interests" as the UN secretary-general warned the Middle East was in a "moment of maximum peril".

By morning, Iran had reopened airports and airspace that were shut during the strikes.

Israel's assault on Gaza began after Hamas Islamists attacked Israel on October 7, killing 1200, according to Israeli tallies.

Israel's military offensive has killed about 34,000 Palestinians in Gaza, according to Gaza's health ministry.

Iran-backed groups have declared support for Palestinians, carrying out attacks from Lebanon, Yemen and Iraq, raising fears the Gaza conflict could grow into a wider regional war.

Australian Associated Press