About 200 protesters were urging the Communist government to resign at a rally in Moldova's capital on Friday afternoon.
The demonstration in front of the main government building comes three days after anti-Communist protesters stormed Parliament and the presidential office.
The protesters - mostly students - were shouting "Down with the Communists!" and "Resignation!" They say they want a peaceful rally.
The protesters were disputing the fairness of elections last weekend that the Communists won.
Prime Minister Zinaida Greceanii has urged students to stay away from the rally. More than 90 people were hurt and 200 arrested in the riots earlier in the week.