Unionists have been stepping up their showdown with the government, with increased disruptions at French oil refineries, ports and transport hubs.
Up to 19,000 people took part in the latest rallies in Paris, far fewer than the first wave of protests against labour reforms about three months ago.
But when several masked protesters began smashing the windows of high street shops, riot police moved in and arrested 16 people.
There were similar scenes in the southwestern city of Bordeaux where about 100 people targeted a police station.
In the western city of Nantes, police used tears gas when protesters targeted the windows of banks.
Unions are furious with proposed labour reforms that they say will reverse decades of workers' rights in France by giving employers more flexibility to hire and fire staff.
Protesters like Geoffroy Rodemann say the government is trying to boost the economy at the expense of its own people.
"We are forced to gather. The only way for the government to listen to us is to put pressure on them. And the only way to put pressure in our manner is to block things - oil refineries, railway workers and all other workers from different professions, to put the country down."
Philippe Martinez is the chief of France's largest trade union, the CGT.
He says an increasing number of workers have responded to the organisation's calls to go on strike.
"We're in a time of a different fight. Workers feel like they are not heard when they demonstrate. So we decided to use different tactics. Democracy must live on in companies."
Transport has been disrupted as rail, air and fuel workers joined the action.
Many have even set up road blocks by setting fire to wooden pallets and tyres at key ports and distribution hubs.
The disruptions have forced motorists like Matthieu Daviaud to wait in long queues for dwindling petrol supplies.
"I was looking for petrol last night thinking there would be fewer people, but there was a lot of them. I was looking for petrol at three stations yesterday and one this morning."
The group overseeing France's petroleum industry says gas supplies have been improving since the government sent police to unblock access to fuel depots.
Francis Duseux, of the French Union of Petroleum Industries, remains confident the country will not experience any kind of fuel shortage.
"If you make a calculation, yesterday we had enough fuel for 115 days. That's four months' worth of reserves available in the whole of France. So far we've used maybe three or four days' worth. So we still have about 110 days' worth. Without provoking it, I'm saying that we're not in a situation of a shortage."
French officials also insist the country will not be experiencing power blackouts, despite 16 of the country's 19 nuclear power stations also affected by the strikes.
Prime Minister Manuel Valls has rejected calls by the CGT to scrap the reforms, saying while he's open to a few tweaks its main features would not be changed.
"It is out of the question to change direction, but there can always be some modifications, some improvements."
After struggling to find enough MPs to back the bill, the government had pushed it through the lower house of parliament by decree.
The final vote is expected in July.
But until then this growing domestic issue remains in danger of worsening before the eyes of the world: the CGT is threatening even more disruptions, this time coinciding with France's hosting of the Euro 2016 football tournament beginning June 10.
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