French police gathered on Wednesday to take a stand against a rise of violence against officers.
But, officers were met by anti-police protesters who attacked a police car with two officers inside.
The police vehicle was set alight in a dramatic unleashing of new anti-police violence.
Paris police chief Michel Cadot sad an investigation for attempted homicide was filed.
Cadot told a news conference about 15 protesters, some masked, that attacked the car and threw a petrol bomb at it.
The male officer was attacked as he got out of the car and was hospitalised while his female partner suffered slight injuries.
Anti-police protesters in Paris and elsewhere in France are claiming police instigated the violence during a series of recent public demonstrations against a controversial labour reform.
Police and protesters clashed during these protests.
While several hundred police officers had gathered to condemn anti-police hate at the Place de la Republique square, protesters began hurling insults and chanted, "Everybody hates the police!"
Police dispersed protesters with pepper spray from the square.
A gathering previously planned at the same area by a group was prohibited due to security risks of "serious disturbances of public order."
Vanina Giudicelli, one of the protesters at the square, said the police gathering was "a real provocation."
"Since the first demonstration on March 9, we notice that they generate the violence. We have been sprayed by gas, hit with batons and arrested."
A total of 53 laws banning demonstrations were issued, including 41 in Paris.
But, some of these laws had been suspended by the Administrative Court.
Jean-Claude Delage, secretary general of the Alliance Police Union, denounced an "escalation of violence" during the labour protests.
French President Francois Hollande said on Tuesday that over 350 police officers were injured in clashes and 60 people were convicted during the labour reform protests.