A video published by police on social media showed thick clouds of white smoke drifting in the air as black-clad protesters hurled projectiles at riot police.
"The right to protest is not the right to break things or act violently. Violent individuals have no place at a peaceful protest," the police said.
Paris police chief Laurent Nunez said thousands of police officers were deployed to uphold order at the demonstration called by a dozen trade unions to protest the pension age hike and deepening social inequality.
Nunez said the rally was expected to draw between 80,000 and 100,000 people, while CGT trade union confederation estimated the attendance at 550,000, according to BFMTV broadcaster.
Violent clashes continued as protesters reached the final point of their march, the Place de la Nation, a RIA Novosti correspondent reported later in the day. The police used tear gas and water cannons, while the militant black block protesters threw stones and fired flares, Molotov cocktails, and improvised explosive devices.
The French Interior Ministry tweeted that over 100 police officers and gendarmes had been injured during the protests, including one seriously burned by a Molotov cocktail.
French Interior Minister Gerald Darmanin told reporters that almost 300 people had been arrested all over the country, 90 of them in Paris. He added that he expected severe punishments for those who had committed violent acts against the police.