As the policemen, some of them in cars with sirens blaring, paraded on the French capital's best-known avenue and in the suburb of Bobigny where the drama occurred, Interior Minister Claude Guéant said he "understands their emotion."
A delegation of the three policemen's unions was received at the interior ministry and demanded that the accused officer should continue to be paid, a representative told AFP.
The unusual show of solidarity by the police came after one of their number was arrested for voluntary homicide.
On Saturday night in the Noisy-le-Sec district of Bobigny one of four policemen tipped off about a fugitive said he was confronted with an armed man who flung a grenade at him. He fired four shots at the man who died shortly afterwards, the policeman said.
However an autopsy showed the victim had been shot in the back, according to court records. The grenade turned out to be a dud.
The 33-year-old policeman pleaded self-defence.
"The police are really up in arms," said Nicolas Comte, leader of the union of which the accused policeman was a delegate.
"We do not deny that justice must be done, but the description of voluntary homicide by the judge is incomprehensible."