"Unfortunately, we had to take action — which was absolutely forced on us — and expel diplomats from three EU countries for taking part in unsanctioned events," Maria Zakharova said on Russian television.
The diplomats were declared "personae non-gratae" on Friday and ordered to leave shortly, after the ministry accused them of participating in pro-opposition rallies on 23 January.
Thousands took part in two straight weekends of protests following the arrest last month of opposition activist Alexey Navalny for violating probation terms. He was given a 3.5 prison sentence on Tuesday that stems from a prior embezzlement conviction.
The Russian presidential spokesman called organisers of demonstrations provocateurs, while Vladimir Putin said that everyone had the right to freedom of opinion but "anything that goes beyond the law is not just counterproductive but dangerous."