The UN on Monday called for “maximum restraint” after a drone attack on an Iranian weapons factory in the central city of Isfahan.
Stephane Dujarric, spokesman for UN Secretary General Antonio Guterres, urged all parties to refrain from any “escalatory action” and “respect the sovereignty and territorial integrity of states”.
Mr Dujarric said Mr Guterres had been following with “concern” reports of incidents over the weekend in Iran.
No country has claimed responsibility for the attack but it is not uncommon for Israel to strike inside Iran.
Iran’s Defence Ministry said two drones had been shot down, while another caused damage to the factory’s roof.
Iran’s official news agency, Irna, reported on Sunday that the drones were aimed at an ammunition factory and had been intercepted by a surface-to-air defence system.
Quoting unidentified US officials and sources, The Wall Street Journal said Israel conducted the drone strike.
"In the course of the previous government in Israel, we saw attacks on Iran's ministry facilities and military personnel," said Ali Vaez, who leads the Iran Project at the International Crisis Group.
"This is basically the Netanyahu government coming back to the implementation of the same policy."
The strike comes as US Secretary of State Antony Blinken is visiting the Middle East, including Israel.
Mr Blinken avoided questions on the attack but said the US supported Israel in defence against Iran.
"Iran is a threat not only of Israel in the region, but increasingly to the world, as we've seen recently, in its provision of drones to Russia to prosecute its war of aggression in Ukraine," he said.
David Makovsky, director of the Koret Project on Arab-Israel Relations at the Washington Institute, said the strike was "a function of a belief that Iran is making progress on missiles and drones, and I think they probably felt the timing is good".
