In Montpellier, southern France, a 12-year-old boy was detained for allegedly aiming a catapult at police headquarters.
A "yellow vest" who was photographing a demonstration in Paris had four fingers blown off, reportedly by a stun grenade thrown by police to deter protesters trying to break through barriers protecting the gates of the National Assembly, the lower house of the French parliament.
Richard Ferrand, the speaker of the Assembly, said an arson attack on his constituency home in Brittany was an example of "intimidation" and rising violence against MPs, although the perpetrators' identity was unknown.
He said more than 60 MPs have received threats or had homes or offices vandalised since the start of the revolt in November, an unprecedented number in post-war France. Some have been given police protection and one MP woke up to find her driveway bricked over.
Ferrand, a close ally of the president, published pictures on Twitter of his scorched living room, saying police had found a blanket soaked in fuel. He wrote: "Nothing justifies violence or intimidation against an elected official." He condemned people who "now feel that it is permissible to commit unlawful or criminal acts against the nation's representatives. This is not a sign of perfect democratic health."
The speaker received messages of support from across the political spectrum, including from Marine Le Pen, the far-right leader, and Jean-Luc Mélenchon, head of the main far-left party.
Anarchists and supporters of extremist groups on the far-right and far-left often join the "yellow vest" protests, along with troublemakers known as "casseurs" intent on causing as much damage as possible.
About 55,000 "yellow vests" joined the protests, with more than 5000 in Paris. The numbers of protesters have dwindled over the weeks, with some put off by violence and attacks on public monuments including the Arc de Triomphe in Paris. Others have chosen to air their grievances in government-sponsored nationwide debates.
Several competing "yellow vest" groups are fielding candidates in May's European elections, but some protesters say the movement must stay out of formal politics.