The recommendation was published by the country’s HAS health authority, which advises the government in the fight against Covid-19.
It comes as cases are surging in France during the Christmas period due to Omicron which spreads faster than any other variant seen so far.
The HAS also recommended that the booster rollout be expanded to now include teenagers who are deemed to be at risk, days after France opened up the vaccination rollout to children aged five and over.
It justified the cut to three months by citing studies showing that vaccines are 80 percent effective for one-to-two months against the non serious symptomatic forms of the Omicron variant, but lose their effectiveness more quickly than with the previous variants.
The effectiveness falls to just 34 percent four months after vaccination with the Pfizer vaccine but the efficacy rose to 75 percent two weeks after a booster dose, it said.
France on Thursday recorded 91,608 positive Covid cases, a record since the start of the pandemic, exceeding the previous high seen in November 2020. However record numbers of tests are being carried out with 6.2 million in the past week.
Unlike some other European countries, President Emmanuel Macron has so far resisted imposing major new restrictions to battle the Omicron variant, hoping that the booster programme will prevent the health system from being overwhelmed.