A mortar shell landed in the compound of the Russian embassy in central Damascus on Sunday.
In a statement, the injuring three people, the Russian foreign ministry said three people were injured. The statement did not say whether those hurt were Russian or Syrian employees.
Rebel forces on the outskirts of the capital regularly fire rockets and mortar roundsinto the centre of the Syrian capital, where many embassies are based.
The Russian mission was damaged in February when a car bomb exploded nearby on a busy highway, killing 50 people.
Russia is a staunch ally of President Bashar al-Assad.