The Iranian defence ministry says it has foiled a drone attack on a military facility in the city of Isfahan.
The ministry said three drones were involved but there were no casualties.
The extent of damage to the site has not been confirmed by the BBC, and there has been no immediate claim of responsibility.
Iran's Foreign Minister Hossein Amir-Abdollahian said the "cowardly" incident was an attempt to destabilise the country.
But he added that the incident would not impact Iran's "determination and intention regarding the peaceful nuclear progress".
Pentagon spokesperson Brig Gen Patrick Ryder said the US military played no part in the strikes, but declined to speculate further, Reuters news agency reported.
The attack comes amid heightened tensions over Iran's nuclear programme and its supply of arms to Russia's war in Ukraine.
