French protesters blockaded Paris's Charles de Gaulle Airport on Thursday in the latest display of anger at President Emmanuel Macron.
Mass strikes brought another day of disruption to train stations, ports and oil refineries in France, after a defiant TV appearance by Mr Macron seemed to intensify the unrest.
The Eiffel Tower and Palace of Versailles were closed, while air passengers carried their luggage on foot after the road to Charles de Gaulle was blocked.
Interior Minister Gerald Darmanin denounced what he said were "unacceptable assaults and damage” at a public building and a police station in Lorient.
Unions vowed to continue their protest against Mr Macron’s bill to raise the retirement age, which was forced through the National Assembly without a vote.
Spontaneous unrest in Paris led activists to embrace the “Be Water” tactics used by the Hong Kong protest movement, with one rally fluidly morphing into another as police tried to keep order.
The phrase is credited to actor Bruce Lee, who was raised in Hong Kong, and it became a hallmark of the mass protests that swept through the Chinese-controlled territory four years ago.
Images from France showed flares being thrown at riot police and activists holding up flaming torches outside a Paris metro station.
About 1,000 people took to the streets in Paris, Lyon and Lille overnight. Hundreds of protesters have been arrested in recent days, further angering the left wing.
“I condemn violence and I appeal for calm … but I also raise the alarm about the question of violence by certain police officers,” said Laurent Berger, head of the CFDT union.
Paris bin collectors have pledged to continue a rolling strike into next week as protesters set fire to piles of rubbish.
Blockades at oil refineries are also set to continue, raising the threat of fuel shortages, while many suburban trains were not running in Paris.
The protests have led to fears of a resurgence of the Yellow Vest violence that paralysed France in 2018 and 2019.
They have also called into question the arrangements for a state visit by Britain’s King Charles III and Queen Consort Camilla next week.
Mr Macron broke his silence on the unrest on Wednesday, when he said in a TV interview that the pension reform should take effect this year despite public opposition.
About 61 per cent of French people said Mr Macron’s intervention would “provoke more anger”, according to a snap poll published by BFM TV on Thursday, while only 11 per cent said it would calm tensions.
Mr Macron was described as unconvincing by 71 per cent and a bad president by 65 per cent, according to the survey.
The French President said he was unwilling to sweep France’s ballooning welfare costs under the carpet. The bill raises the retirement age from 62 to 64 in a flagship measure of the president’s second term.
"Do you think I enjoy making this reform? No," Mr Macron said, but “we must go ahead because it's in the higher interest of the nation."
Mr Macron’s government narrowly survived a no-confidence vote on Monday that would have sunk the pension bill and forced Prime Minister Elisabeth Borne to resign.
France’s Constitutional Court could yet decide the fate of the bill after Mr Macron’s opponents filed complaints.