The National Observatory Against Islamophobia said 116 anti-Muslim incidents had been reported to authorities since the January 7-9 shooting spree by three French jihadists that killed 17.
The two-week tally was more than double the number of incidents recorded for the full month of January 2014, the observatory said, reporting 28 attacks on places of worship and 88 threats.
The observatory's president, Abdallah Zekri condemned the "acts of hatred towards French people of the Muslim faith, the immense majority of whom respect the values of the Republic and secularism."
"This situation is unacceptable and we're asking the authorities to go beyond the reassuring speeches and act to put an end to this scourge," he said.
Islam is France's second-biggest religion with an estimated 3,5-5 million followers. Several mosques have been attacked since the Paris killings, which began with a massacre at Charlie Hebdo satirical weekly and ended with a bloody hostage taking in a Jewish supermarket.