The unrest has shone a light on tensions in deprived urban areas of France, where local youths often complain about heavy-handed policing and brutality.
The officer had initially claimed he acted in self-defence while trying to arrest the 22-year-old in the city of Nantes on Tuesday, but later told investigators he had fired his weapon by accident.
“He recognises he made a statement that did not conform with the truth,” his lawyer Laurent-Franck Lienard told AFP.
The victim, identified as Aboubakar Fofana, died from a single bullet wound to the neck on Tuesday evening after police stopped him in his car in the Breil neighbourhood of Nantes — home to a large public housing estate with a history of gang violence.
Police initially said that Aboubakar, who was under surveillance for suspected drug trafficking, had resisted arrest and tried to reverse his car into an officer.
But a witness who spoke to AFP said the car was stationary when the policeman opened fire.
The policeman, who has been granted conditional release, told the IGPN police oversight body under questioning that “it was an accidental shot” that killed Aboubakar.
Some 35 more vehicles were torched in Nantes before dawn Saturday in the fourth night of rioting, after gangs of youths set fire to 52 cars — including the mayor’s personal vehicle — and several buildings overnight Thursday-Friday.
Security services fired teargas Saturday in two suburbs after coming under Molotov cocktail fire.
Calm was restored before first light, AFP reporters said.
There have been more than a dozen arrests over the violence, including in Garges-les-Gonesse, the Paris suburb where Aboubakar grew up.
Three men were given suspended four-month prison sentences on Friday for taking part in the violence after the shooting.
In a separate development, two off-duty officers, a husband and wife, were attacked Wednesday night in front of their three-year-old daughter in a northeastern suburb of Paris shortly after leaving a dinner party.
French security forces are frequently treated as targets and they struggle to combat violent drug-dealing gangs.
A police source said the attackers recognised the policewoman because she had recently stopped them for an ID check in the crime-ridden area of Aulnay-sous-Bois.
President Emmanuel Macron denounced the attack as an “appalling and cowardly act” and vowed the suspects would be “found and punished”.
One of them has been arrested while the second remains on the run.
In a bid to defuse tensions, Prime Minister Edouard Philippe visited Nantes on Thursday where he promised “the fullest transparency” about the circumstances of the young man’s death.
On Thursday evening, around 1,000 people marched in Nantes calling for “justice for Abou” and demanding clarity about the circumstances of his death.
There have been fears that the unrest could spread.
In 2005, riots erupted across the country following the deaths of two black teenagers who were electrocuted in a Paris suburb while hiding from the police.
Anger over policing bubbled over again last year when a young black man in another Paris suburb suffered severe anal injuries caused by a truncheon during his arrest.