Security forces deployed across the country to try to remove any blockades as fast as possible, officials said on Wednesday, meaning that France was, for now, not blocked.
Nearly 200 protesters were arrested across the country, and there were some scuffles.
Many demonstrators vented their anger against President Emmanuel Macron, who is already facing political turmoil after the parliamentary opposition united to defeat his government on Monday.
In Paris, police fired tear gas on youth protesters blocking the entrance to a high school and firefighters removed burnt objects from a barricade.
Police said they had stopped a large group of about 1000 protesters entering the Gare du Nord train station in the city.
Interior Minister Bruno Retailleau told reporters that protesters had torched a bus in the western city of Rennes.
He also said some protesters had attacked police with heavy cobblestones, but did not specify where.
Retailleau warned that protest rallies scheduled for later in the day could be infiltrated by hard-line, ultra-left groups and become violent.
The Block Everything movement - a broad expression of discontent with no centralised leadership and an ad hoc organisation by social media - sprung up online in May among right-wing groups, researchers and officials said, but has since been taken over by the left and far left.
Parliament ousted Prime Minister Francois Bayrou in a confidence vote over his plans to tame the country's ballooning debt.
Macron appointed his fifth prime minister in less than two years on Tuesday, picking a close ally, Sebastien Lecornu, which outraged left-wing politicians.
In the western city of Nantes, protesters blocked a highway with burning tires and bins. Police used teargas to disperse people trying to occupy a roundabout.
In Montpellier, in the southwest, police scuffled with protesters who had set up a barricade to block traffic at a roundabout.
Police used tear gas to disperse the protesters, some of whom threw various objects at them.
Highway operator Vinci reported traffic disruptions on highways throughout the country, including Marseille, Montpellier, Nantes and Lyon.
The Block Everything movement reflects popular discontent with what protesters deem a dysfunctional ruling elite preaching a painful gospel of austerity.
It is drawing comparisons to the 2018 "Yellow Vest" protests, which arose over fuel price hikes but morphed into a broader movement against Macron and his plans for economic reform.
About 50 hooded people tried to start a blockade in Bordeaux, while in Toulouse, in the southwest, a fire was quickly extinguished but still disrupted train traffic, the interior minister, Retailleau, told reporters.
He said 80,000 security forces had been deployed throughout the country, including 6000 in Paris.
French media had reported that 100,000 people were expected to take part in the demonstrations.
