The Iranian defence ministry on January 29 conceded there was a drone attack on a military facility in the central city of Isfahan a day after it occurred, but said the attack was foiled.
Of the three drones involved late on January 28, one was destroyed by air defence systems and two were caught by "defence traps" but caused minor damage to a building, the ministry added.
Hossein Amir-Abdollahian, Iran's foreign minister, described the incident as "cowardly" and said it was an attempt to destabilise the country.
There are unconfirmed reports that the attacked facility, 440 kilometres south of Tehran, is partly used as a research centre and production facility for drones.
Iran is known to have provided kamikaze drones to Russia for use in its war in Ukraine. Kyiv has previously warned Tehran that it could suffer unspecified consequences resulting from its provision of military drones to the Kremlin.
Following the drone attack on the Iranian facility, a senior aide to Ukrainian President Volodymyr Zelenskiy hinted the incident was linked to Iran's role in arming Russia for the war. "Explosive night in Iran," Mykhailo Podolyak tweeted. "Did warn you."
One US official, speaking on condition of anonymity, told Reuters news agency that it appeared Israel was involved in the attack.
The Wall Street Journal, citing several unnamed sources in the US, carried an article saying Israel was behind the attack.
Pentagon spokesperson Brig Gen Patrick Ryder said the US military played no part in the strikes, but declined to speculate further.
Local authorities did not comment on activities at the site, but called it a "workshop". Iran’s official news agency IRNA said the strike targeted "an ammunition manufacturing plant".
In a separate incident on January 28, IRNA reported a fire broke out at an oil facility near the northwestern city of Tabriz. No details about the cause were reported.
Recent years have brought a number of explosions and fires at Iranian military, nuclear and industrial facilities. At least some of them have been caused by sabotage.