On Friday morning, in the latest confrontation between the authorities and protesters, police cleared young opponents of the reform from a council-owned building they had been occupying since 1 May in the western city of Rennes.
One protester was charged with "rebellion".
There were clashes between protesters and police on several demonstrations against the bill on Thursday.
Blaming a "minority of activists", Interior Minister Bernard Cazeneuve said that 18 police officers or soldiers had been injured but, as usual, gave no figures for injuries to protesters.
Unions threaten more protests against labour bill
Thursday's demonstrations, which took place in most major cities, were smaller than those on the four previous days of action against the bill but union leaders have called for more strikes and rallies on 17 and 19 May.
Philippe Martinez, of the CGT labour federation, called on the movement to switch to a higher gear and his union has issued indefinite strike calls over disputes involving railworkers, dockers and seafarers.
No-confidence motions fail in parliament
The government faced opposition in parliament on Thursday, too, because of its use of an enabling decree, known as 49-3, to bypass the lower house of parliament and force the measure through its first reading there.
A motion of no confidence proposed by the right-wing opposition failed to pass, despite the support of 15 left-wingers, mainly from the Communist Party and Jean-Luc Mélenchon's Left Party.
Rebel Socialist MPs tried to table their own no-confidence motion but failed to gather the 58 signatures needed.
Of the 56 who did sign, 28 were Socialists, among them former culture minister Aurélie Filipetti and former education minister Benoît Hamon.
Socialist Party rift widens
Prime Minister Manuel Valls called their effort "serious, even if it has failed" and party national secretary Jean-Christophe Cambadélis said he would ask its ethics committee to consider disciplinary action against them.
The rebels have ruled out leaving the party, however.
"The Socialist Party is not the personal property of François Hollande of Manuel Valls," one of them, Laurent Baumel, told BFMTV on Wednesday. "When I defend my position on the question of labour reform I have the impression I'm defending the Socialist Party's natural position."
Rebel leader Christian Paul threatened to try to censure the government again if it uses the 49-3 provision to push the bill through its second reading in the National Assembly.
Before that it must be debated in the Senate, which is controlled by the right.
The Senate speaker, a member of the main right-wing Republicans, has declared his intention of restoring the bill to its initial version, reinstating measures that the government dropped to win the support of "reformist" unions, notably the CFDT federation.
"The first version was fine by us," Gérard Larcher told Le Parisien newspaper. "It was going in the right direction even if it wasn't perfect. I could have proposed it when I was labour minister."
Statements like that seem designed to deepen the divisions in the Socialist Party.
Calls for presidential primary of the left
The rebel's motion failed to win signatures from supporters of Lille mayor and former labour minister Martine Aubry, although they have criticised the Valls government.
But Aubry's supporters have joined calls for a primary of the left, possibly involving the Communist Party and the Greens, before next year's presidential election.
Although the Socialists were the first French party to organise a primary, in the run-up to the 2012 presidential poll, the party leadership has said there will not be one if Hollande, as incumbent, decides to stand again.
The harder-line rebels are also pushing for a primary.
Former economy minister Arnaud Montebourg, who, like Aubry, stood in the 2012 one, has hinted he might stand again and may make his intentions clearer on Monday when he joins Paul and others on the Socialist left for an annual hike up a mountainside.
Activists in the Nuit Debout (Up All Night) movement hope that their protests and the opposition to the labour reform will shake up the French political scene as the Indignados sit-in did in Spain and the Syntagma Square protests did in Greece.
At present the Socialist left does not seem tempted to throw in its lot with them or with the hard-left Left Front, despite appeals to join its ranks.