Russian Ministry of Foreign Affairs. AFP
Greece's ambassador was summoned to the Russian foreign ministry and told the diplomats had eight days to quit the country, said a ministry statement.
The decision was "the direct consequence of unfriendly actions taken by the Greek authorities", said the ministry.
The statement referred specifically to the delivery of weapons and military material to Ukraine and the expulsion of Russian diplomats from Greece.
Athens expelled 12 Russian diplomats in April, following Moscow's military operation in Ukraine, launched in late February.
Despite the two countries historical ties, because of their shared Orthodox Christian religious heritage, Athens has joined other Western nations in condemning the Russian military operation.
Western countries around the world have expelled several hundred Russian diplomats over the issue, and Russia has replied in kind.