Romanian Prime Minister Emil Boc has called for dialogue and an end to violence after four days of protests against austerity cuts.
Dozens of people were hurt on Sunday, as demonstrators and riot police clashed for a second day running in the capital Bucharest.
The rallies began in support of an official who quit in protest against health care reforms.
But they have grown into a broader hostility towards government policies.
The alliance of opposition parties has called for early elections.
More than 1,000 demonstrators rallied in University Square in the centre of Bucharest on Sunday, the scene of violence the night before.
Demonstrators threw stones at riot police, who again responded by firing tear gas.
A number of people were arrested, with officials saying that most of the trouble makers were young football fans.
Peaceful protests were reported in a number of towns and cities across the country on Sunday, including Cluj, Timisoara, Brasov and Arad, as demonstrators called for the resignation of the government and of President Traian Basescu.
Dozens of demonstrators were also said to have gathered in the centre of the capital on Monday.
The government called an emergency meeting after Sunday night's clashes.
Speaking on Monday, Prime Minister Emil Boc expressed sympathy with those struggling under austerity measures.
"The crisis has been harsher than we imagined," he said, but added that the violence "cannot be tolerated".
The protests follow cuts to salaries, benefits and higher taxes but the unlikely catalyst was the resignation of popular health official Raed Arafat.
The Palestinian-born doctor came to Romania in the 1980s, and is a well-known and much-liked figure, due to the practical changes he made to improve the emergency services, the BBC's Nick Thorpe reports.
Dr Arafat stepped down as Health Ministry undersecretary last Tuesday, after a series of public attacks on him by President Traian Basescu, our correspondent adds.
Dr Arafat opposed government measures to partially privatise Romania's shaky health care system.
President Basescu later announced that he was scrapping the unpopular reform, but that has failed to soothe the demonstrators' anger, our correspondent says.