Twenty-four policemen were injured in the protests, including three seriously in Paris, Interior Minister Bernard Cazeneuve said.
A total of 124 people were arrested nationwide, Cazeneuve said, with protests also taking place in Lyon, Marseille, Toulouse, Rennes, and Nantes.
Militant action that has marked the recent protests against the labour reform bill began early in the day when students from a Paris university blocked access to the port of Gennevilliers on the Seine, near Paris.
Around 200 students piled up tyres to block access to the port before police turned up.
Environ 200 étudiants de Paris 8 entament une opération de blocage du port de Gennevilliers pic.twitter.com/5ULtYNuVhq— jgbontinck (@JGBONTINCK) April 28, 2016
Hundreds of strikers, mainly dockworkers, set up flaming roadblocks at all the main access routes around the port of Le Havre, the all-news BFMTV channel reported.
Riot police were sent out in force, with recent demonstrations also ending up in running battles between police and protesters.
The government's changes are basically aimed at making it easier for companies to hire and fire workers and make rules around working hours less rigid.
However opponents argue that workers will be left worse off and in a more precarious situation. They argue it shouldn't be workers who pay the price for high unemployment, but company chiefs and their profit margins.
Since the first protest on March 9th the numbers turning out to pound the streets and shout their opposition have fallen, thanks in part to the government caving in on some of the more controversial aspects of the reform.
While the watered down version of the reform may have appeased the more reformist unions, it left employers groups and business leaders fuming and threatening all out revolt.
"The current bill, which is totally unacceptable, spells insecurity and social setbacks for workers and youths," a joint union statement said.