Lebanese President Michel Aoun called on the army and security commanders to restore calm and order after clashes erupted on Saturday between angry protesters and security forces near parliament in central Beirut.
Protesters flung stones, traffic signs and tree branches at security forces, who responded with water canons and tear gas.
The protest movement rocking Lebanon since October 17 has revived this week, over delays in forming a new cabinet to address the country's growing economic crisis. Protesters are furious at a ruling elite that has steered the country towards its worst economic crisis in decades.
No progress appears to have been made towards a final lineup, which protesters demand be comprised of independent experts and exclude all traditional political parties.
On Saturday afternoon, demonstrators set out from various spots in Beirut in a march towards the city center under the slogan "We won't pay the price".
But before they all converged near the road leading to parliament, dozens of protesters flung rocks and plant pots filled with earth at the police guarding the institution, local television channels showed.
Security forces sprayed young men with two water cannons and lobbed tear gas over a metal fence to disperse remaining protesters on the wet tarmac.
"A direct and violent confrontation is taking place with anti-riot police at one of the entrances to parliament," the Internal Security Forces said on Twitter.
"We ask peaceful protesters to keep away from the site of the rioting for their safety."
An AFP photographer saw young men uproot parking meters.
He also saw around 10 people faint from the tear gas.
The Lebanese Red Cross said more than 60 people had been treated for injuries, with at least 40 others taken to hospital.
Interior Minister Raya el-Hassan said it was unacceptable for protesters to attack security forces.
“I always asserted the right to protest, but for the protests to turn into a blatant assault on the security forces, on public and private property, is condemned and not acceptable at all,” she said in a tweet.
A female protester named Maya, 23, said she was attending the protest because politicians still seemed to be ignoring demands for an overhaul of the old political class.
"I'm here because after more than 90 days in the streets, they're still squabbling over their shares in government... It's as if they didn't see our movement," she told AFP.
"Popular anger is the solution," the young protester said.
Firefighters tackled a blaze which engulfed a protest camp in the centre of the city, where burning tents sent plumes of smoke into the air.
It was not immediately clear what caused the fire.
Forming a new cabinet is often convoluted in Lebanon, where a complex system seeks to maintain balance between the country's many political parties and religious confessions.
But protesters say they want to scrap the old system, and demand only impartial technocrats staff a new government to address their growing economic woes, including a severe liquidity crisis.
The last government stepped down under pressure from the street on October 29, but has remained in a caretaker capacity until a new cabinet takes shape.
The World Bank has warned that the poverty rate in Lebanon could rise from a third to a half if the political crisis is not remedied fast. The Lebanese pound has lost nearly half its value, while dollar shortages have driven up prices and confidence in the banking system has collapsed.