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 attack came days after Iran launched an unprecedented drone and missile strike on Israel. (AP PHOTO)
"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.
Iran told the UN Security Council that Israel must stop any further military adventurism against it. (AP PHOTO)
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.
"It is absolutely necessary that the region remains stable and that all sides restrain from further action," EU Commission head Ursula von der Leyen said.
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".
IAEA can confirm that there is no damage to — IAEA - International Atomic Energy Agency ⚛️ (@iaeaorg) #Iran's nuclear sites. DG @rafaelmgrossi continues to call for extreme restraint from everybody and reiterates that nuclear facilities should never be a target in military conflicts. IAEA is monitoring the situation very closely. pic.twitter.com/4F7pAlNjWMApril 19, 2024
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.
