While hundreds of thousands protested peacefully in street marches in scores of cities on Saturday, violent fringe groups targeted public buildings, looted luxury boutiques and supermarkets and attacked police vehicles and officers.
President Emmanuel Macron said there was "no room for violence" after riots broke out in several cities, with protesters blocked from marching on government buildings in Paris.
In Limoges, the city hall was set ablaze; in Marseille, black-clad protesters broke into city hall and defaced the building with anarchic graffiti, and in Lyon, protesters torched the city's tourist office.
Prime Minister Sebastien Lecornu said the government would not be "intimidated" by violence, and blamed the unrest on the "ultra-left" and criminals.
"To those who clearly want to use this violence as a 'warm-up' before the presidential election, I say clearly: We will not let ourselves be intimidated. No one will impose their political agenda through violence," he wrote in a post on X.
Some 1200 people were arrested, Lecornu added while visiting the sites in the evening.
Around 550,000 people had participated in the demonstrations across the country, Interior Minister Laurent Nunez said. The CGT union told Reuters it estimated protesters at 800,000 people.
Macron vowed to prosecute and punish people who carried out the attacks.
"We will all stand united against the sowers of chaos, who only seek to undermine our institutions and prevent those who peacefully express their demands from doing so," he wrote on X.
Belgium, Portugal and Italy also faced smaller-scale protests on Saturday as living costs rise in Europe, while protesters in Albania again rallied against perceived government corruption, a lack of jobs and poor education standards.
Protesters said most people had marched peacefully, and put much of the violence down to troublemakers who had set out to cause damage and clash with the police.
Most protests kicked off around midday, with some beginning before the official start of the demonstrations.
In Paris, police fired tear gas rounds as they retreated in the face of mostly young protesters, many of whom were dressed in black and wore hoodies, masks and goggles.
Rioters tried to break into the Galeries Lafayette department store, smashed up banks, ransacked a Lacoste store as well as other boutiques and looted an SFR mobile phone shop. Protesters set objects ablaze all day, including numerous cars.
Several hundred people protested in Brussels, against rising education costs and reforms they fear will make higher education less accessible.
In Albania, police fired what appeared to be rubber bullets at protesters during a fifth day of mass student demonstrations calling for Prime Minister Edi Rama to step down.
In Portugal, tens of thousands took to the streets of Lisbon following days of unrest to protest against housing and other living costs. Housing prices in Portugal have doubled since 2017, fuelling one of the worst affordability crises in Europe.
In Italy, a march against high costs of living in Milan degenerated into disorder, with police clearing the central cathedral square with tear gas. Police in Bologna used water cannons to try to disperse crowds and made seven arrests.
The protests in France began in September at high schools in Paris' working-class northern suburbs, where anger over teacher shortages and shabby facilities evolved into a broader movement focused on inequality, public spending and living standards.
In Paris on Saturday, protesters in high-visibility vests blocked streets, recalling the Yellow Vest movement that marked Macron's previous term in office.
Saturday's protests eclipsed the size of the crowds at the peak of the Yellow Vest movement, though they were far lower than the levels seen at the protests in 2023 against Macron's pension overhaul.
