Eight hundred police officers were deployed at the mosque and in the area around the U.S. Embassy, Radio France Internationale reported. Officials said they hoped to stop demonstrations over the decision by a French satirical magazine, Charlie Hebdo, to publish cartoons showing the Prophet Muhammad naked.
The detainees Saturday included several women.
Last week, 150 people were arrested for holding a demonstration without a permit outside the mosque. A young railway worker was sentenced to three months Saturday for carrying a baton he said was to be used if Jewish extremists attacked the Muslim gathering.
Interior Minister Manuel Valls said "very determined people" were trying to cause trouble. He praised Muslim leaders who appealed for calm.
In La Rochelle in western France, police charged a man who allegedly demanded the head of Stephane Charbonnier, editor of Charlie Hebdo. The call was made on an Islamist website.
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