Several dozen masked individuals, chanting "State of emergency, police state!", threw glass bottles and a crash barrier at police on Paris's Place de la République on Sunday afternoon.
Police responded with teargas and arrested 100 people, officials said.
Interior Minister Bernard Cazeneuve this week warned police and officials not to abuse the powers granted to them by the state of emergency in several cases.
Earlier several thousand people formed a human chain across the city and shoes were placed on the square to represent people who would have demonstrated if Sunday's planned march had not been cancelled.
A British-based organisation on Sunday announced that it had replaced 600 posters supporting Cop21 on electronic hoardings belonging to the JC Decaux company.
The Brandalism group accused the companies that had sponsored them - including Air France, Engie (formerly GDF Suez), Dow Chemicals and JC Decaux itself of being major polluters and "pretending to be part of the solution, while being part of the problem".