A hand grenade thrown at the French embassy in Athens Thursday morning by unknown assailants slightly injured a policeman, local broadcaster Skai and state media reported.
The assailants arrived at the embassy on a motorbike and fled through the city's narrow alleys after the attack.
Police told reporters at the scene that the underground organization "Revolutionary Cult" or a group called "Revolutionary Battle" could be responsible.
Radical left-wing groups committed similar attacks using hand grenades against police in the past.
The French embassy is located in the centre of Athens, opposite the parliament building.