Paris police authorities said they have banned a planned union demonstration in the capital on Thursday, after previous such marches descended into violence.
The police said in a statement Wednesday they had "no choice" other to than to ban the demonstration against the controversial labour reforms of President Francois Hollande's Socialist government.
Earlier in the month, Hollande had threatened to ban such demonstrations as scenes of violence in the capital marred France's image as it hosts the Euro 2016 football championships.
At the last major demonstration, on June 15, 40 people were hurt and dozens arrested as masked protesters fought running street battles with police.
Police fired water cannon in the south of the capital to quell rioters as "several hundred" masked protesters lobbed objects at security forces in bloody scenes.
Authorities and organisers gave wildly different figures for the turnout, with unions saying 1.3 million people had turned out across France but police estimating the crowds at 125,000 or more, some 80,000 of them in Paris.
France is already on high alert over terrorism during the Euro 2016 football tournament and violent demonstrations have stretched pressurised security forces to breaking point.
The labour market reforms are aimed at making the job market more flexible and reducing high unemployment but critics them see as too pro-business.
The unions had demanded permission to march in Paris, but the government insisted that a stationary rally would be easier to control.