Iranian air defences have shot down three small drones over Iran's city of Isfahan, after Iran's state media reported explosions in the central province of Isfahan on Friday.
US media quoted officials saying Israel had carried out retaliatory strikes on its arch-rival.
Air defence systems over several Iranian cities were activated, state media reported, after the country's official broadcaster said explosions were heard near the city of Isfahan.
Israel had previously warned it would retaliate after Iran fired hundreds of missiles and drones at Israel almost a week ago, in retaliation for a deadly strike -- which Tehran blamed on its foe -- that levelled Iran's consular annex at its embassy in Syria.
There had been no reaction from Israeli or Iranian officials to the overnight strikes and the extent of the damage remained unclear.