But French vehicle manufacturers grouped in the CCFA trade body said they expected sales to improve by the end of the year, to show an annual fall of 8.0 percent.
The president of the CCFA, Patrick Blain, told a press conference: "We think that we are approaching the bottom."
Orders placed in June had steadied, he said.
However, the slump of the market for cars sold continued in June, when sales overall fell by 9.0 percent on a 12-month comparison, unadjusted for seasonal factors.
In June, French and foreign manufacturers sold a total of 190,199 cars. Sales by French group PSA Peugeot Citroen fell by 9.5 percent in the month and by rival French group Renault/Dacia by 3.6 percent.
In the first half of the year the overall French market shrank by 11.3 percent to 930,320 vehicles with French manufacturers doing worse than foreign brands.
Sales by PSA Peugeot Citroen were particularly hit, falling 14.3 percent.
PSA is undergoing deep restructuring and last week was the subject of a report, later denied, that it might fall under the control of its partner General Motors.
Sales by Renault fell by 8.1 percent in the six months.