Police in Podgorica said they were forced to respond to protesters outside the parliament building on Sunday evening after members of the crowd started to throw stones and flares.
The unrest took place in front of the building, which some of the protesters tried to enter after breaking through a fence. Officers used tear gas to try to keep the protesters back.
"We seek the resignation of the government and formation of an interim one," said Andrija Mandic from Montenegro's main opposition bloc, the Democratic Front, which organized the protest. He urged the demonstrators to refrain from violence, but also urged them to persist.
"If the left-wing government does not resign by Saturday, even bigger protests will be staged, said Mandic. "This is an ultimatum and it is irrevocable."
The country's ruling coalition, led by Prime Minister Milo Djukanovic and opposition parties, on Sunday agreed to call an extraordinary session of the parliament's security committee on Tuesday to examine whether police had used excessive force at an opposition rally a day earlier.
Tents removed over state threat
Democratic Front supporters set up tents outside parliament three weeks ago, but these were removed by police on Saturday morning. Some 11 people were detained, including opposition lawmakers.
The removals took place after the National Security Council concluded that "there were activities that threatened the constitutional order, stability and security of the citizens and their property."
Montenegro is a candidate for European Union membership and is also awaiting an invitation to join NATO later this year. Djukanovic's Democratic Party of Socialists (DPS) has accused the Democratic Front of trying to destroy the country's "constitutional order and stop it in its aim to join NATO," it said in a statement on Sunday.
Demonstrators have called for a transitional government in place of Djukanovic, who has been at the center of power since the early 1990s.
rc/cmk (AFP, AP, Reuters)