Iran acknowledged for the first time on Saturday that it had supplied Moscow with drones but said they were sent before the war in Ukraine, where Russia has used drones to target power stations and civilian infrastructure.
Iranian Foreign Minister Hossein Amirabdollahian said a "small number" of drones had been supplied to Russia a few months before Moscow's forces invaded Ukraine on 24 Feb.
In Iran's most detailed response to date on the drones, Amirabdollahian denied Tehran was continuing to supply drones to Moscow.
"This fuss made by some Western countries that Iran has provided missiles and drones to Russia to help the war in Ukraine - the missile part is completely wrong," the official IRNA news agency quoted him as saying.
"The drone part is true and we provided Russia a small number of drones months before the Ukraine war," he said.
In recent weeks Ukraine has reported a surge in drone attacks on civilian infrastructure, notably targeting power stations and dams, using Iranian-made Shahed-136 drones. Russia denies its forces have used Iranian drones to attack Ukraine.
Last month, two senior Iranian officials and two Iranian diplomats told Reuters that Iran had promised to provide Russia with surface-to-surface missiles, in addition to more drones.
The official IRNA news agency quoted Amirabdollahian as saying Tehran and Kyiv had agreed to discuss allegations about the use of Iranian drones in Ukraine two weeks ago but the Ukrainians did not show up at the agreed meeting.
"We agreed with the foreign minister of Ukraine to provide us with documents they have that Russia used Iranian drones in Ukraine," Amirabdollahian said, but the Ukrainian delegation pulled out of the planned meeting at the last minute.
The Ukrainian Foreign Ministry did not immediately reply to a written request for comment.
The Iranian foreign minister repeated that Tehran would "not remain indifferent" if it were proven that Russia had used Iranian drones in the war against Ukraine.
The European Union last month agreed new sanctions on Iran over its drone deliveries to Russia, and Britain imposed sanctions on three Iranian military figures and a defence manufacturer for supplying Russia with drones to attack civilian and infrastructure targets in Ukraine.