The protests on Saturday, which were largely peaceful through the afternoon, continued for a third weekend after riots and looting on October 17 that caught security forces off guard, leaving a trail of damage to shops, public buildings and businesses across the country.
Riot police charged to disperse small groups of rioters at the end of the Paris march, and fired tear gas in Lyon, France's third-largest city, and in Toulouse in the southwest. There were also tensions at the end of unauthorised protests in Marseille, but calm returned as night fell.
"Security forces held their ground and protected city centres. Public order was maintained," Interior Minister Laurent Nunez told reporters after the marches, adding that police had faced "a great deal of violence".
Authorities were now bracing for scattered unrest later in the evening, amid what he said were calls for insurrection on Halloween night.
The protests in France have inspired youth-led "Gen-Z" protests across Europe, with demonstrations in several German cities on Saturday. There were also protests in Italy.
The marches brought together students - who began mobilising in September - with trade unions and a smaller contingent of anti-establishment Yellow Vest protesters, united by complaints over the cost of living, high fuel prices, rising inflation and President Emmanuel Macron's government.
Far-left leader Jean-Luc Melenchon, whose ratings have risen in recent weeks ahead of next April's presidential election, marched at the head of the Paris demonstration.
France's top administrative court had upheld a ban on a march between the landmark Paris squares of Nation and Bastille, rejecting a challenge from unions. Authorities instead authorised a route along boulevards on the eastern edge of the capital, away from central shopping districts.
Turnout was lower than for the previous two Saturdays of protests, with 320,000 protesters nationwide, including 70,000 in Paris, the Interior Ministry said. That compares with 410,000 the week before and 550,000 on October 17.
The Interior Ministry said in a statement that "radical elements" intent on damage and looting had attempted to break away from marches in cities including Bordeaux, Toulouse, Lyon and Marseille, but were thwarted by security forces.
Authorities have warned that Halloween masks could be used to conceal the identities of rioters.
With public debt nearing 120 per cent of economic output and borrowing costs rising, Macron's government faces mounting pressure to curb spending, limiting its room for manoeuvre.
The protests gathered momentum in late September as Macron's minority government opened talks on its 2027 budget. Students angered by the deteriorating state of schools, overcrowded classrooms and a university admissions system widely viewed as unfair have since been joined by trade unions and a resurgent Yellow Vest movement demanding action on living costs.
The French government's promises to reform education and ease fuel costs have failed to calm discontent.
