The demonstration against Israel's Gaza offensive that has killed more than 1,000 Palestinians comes after other protests last weekend in Paris and a suburb town that had also initially been banned descended into chaos.
Organisers of today's protest had tried going to court to get the ban overturned, but they were unsuccessful and Interior Minister Bernard Cazeneuve warned that they would be held "responsible for any unrest... And liable to penal sanctions."
After an initial peaceful start, police began firing tear gas after some hooded protestors threw cans and other objects at them, and several journalists were roughed up.
A police source said 40 people were detained, adding that they were under strict orders to take in people who made anti-Jewish statements or gestures.
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Some 2,000 police were mobilised, and many of them were present on the square to stop the rally from moving on to other parts of the French capital.
Elsewhere in the country, nearly 10,000 people turned up in the eastern city of Lyon for a similar protest, though it was not banned and went off peacefully.
In the southern cities of Marseille and Nice, hundreds also turned up in support for Palestinians.
The conflict has stirred up huge passions in France -- home to the largest Muslim and Jewish communities in western Europe with around five million Muslims and half a million Jews.
In Sarcelles last weekend, Jewish businesses were looted and in one violent Paris demonstration several weeks ago, protesters tried to storm two synagogues, raising concerns among the Jewish community about anti-Semitism.