Colonel Gilles Jaron, a French defence ministry spokesman, said the French force reached its full deployment of 1200 yesterday, with some entering the west of the country from neighbouring Cameroon.
Jaron said other French troops are leaving Bangui, the capital, on a reconnaissance mission to the north, but declined to give details.
France had pledged to increase its presence well before Christian militias attacked Bangui at dawn on Thursday. Clashes between Christian militias and mostly Muslim former rebels left at least 281 people dead.
CAR's shaky interim authorities yesterday ordered all forces except foreign peacekeepers and the presidential guard off the streets of Bangui, where gunfire has eased but attacks on civilians are continuing.
A senior UN aid official said French and African peacekeepers must push into neighbourhoods where "senseless" Muslim-Christian killings are rife, and not just control the main roads of the capital.
Clashes resumed in Bossangoa, about 300km (190 miles) north of Bangui, a day after an African peacekeeper was killed there, a witness said. It was reported that at least 30 people had been killed.
The order for gunmen to return to barracks in Bangui was read on national radio.
A reinforced French force stepped up patrols of the dilapidated capital and warplanes flew low overhead. But residents and rights groups said killings had taken place on Friday in alleys away from the main roads.
"Peacekeepers are patrolling the main roads. This is helping keep the looting down. But the atrocities are inside the neighbourhoods," said Amy Martin, head of the UN Office for the Co-ordination of Humanitarian Affairs. "The level of atrocities and the lack of humanity, the senseless killing, defies imagination."
A French defence ministry source said: "There were patrols all night, including some on foot. We are going everywhere - on the main roads but also to locations we have been directed to by humanitarian organisations and the civilian population."
French forces began deploying to the north and west of the country yesterday.
CAR has been gripped by chaos since mainly Muslim Seleka rebels seized power in March, leading to tit-for-tat violence with "anti-balaka" militia formed by the Christian majority in response to abuses by former rebels.
Michel Djotodia, leader of the Seleka ex-rebel alliance, is CAR's interim president, but has struggled to control his fighters, many from neighbouring Chad and Sudan.
An attack on Bangui on Thursday by "anti-balaka" forces and gunmen loyal to ousted president Francois Bozize ignited the worst violence in a year of crisis. It coincided with the UN Security Council authorising France to use deadly force to help African peacekeepers struggling to restore order.
The local Red Cross said by Friday evening that 281 bodies had been collected from the city's streets, but many more were expected to be brought in over the weekend.
Pastor Antoine Mbao Bogo, president of the organisation, said: "We see the international forces, but there has not been any real impact on the ground. It will take time."
About 10,000 Bangui residents have fled to the airport, where French troops are based, in search of safety. Thousands more have gathered in churches and other buildings.
Additional reporting by David Lewis