Announced in the government's official gazette, the new rules require candidates for citizenship to "prove knowledge of the French language consistent with understanding the essential points needed to manage daily life."
Candidates previously had their language skills tested in interviews with government officials, but will now be required to provide evidence of French-language skills "by producing a diploma or certificate delivered by a state-recognised organism."
The new rules take effect in January.
Quoting an interior ministry estimate, business newspaper Les Echos reported on Wednesday that about one million foreigners living in France did not speak French.
It said the French government was growing increasingly concerned over the issue and was spending €60 million ($83 million) to promoteFrench-language skills and integration among immigrants.
France grants citizenship to about 100,000 candidates every year, according to official figures.