SARCELLES, France — Several hundred pro-Palestinian demonstrators rampaged through the Jewish quarter of this northern suburb of Paris in July, some chanting, “Death to Jews.” As the rioters attacked a funeral home and set fire to a pharmacy, a band of young Jews formed a human shield in front of the city’s main synagogue, brandishing motorcycle helmets as weapons.

Foot soldiers of a French offshoot of the Jewish Defense League, a far-right Zionist group that advocates muscular self-defense in the face of violence and anti-Semitism, they faced off with the crowd as protesters clashed with riot police officers.

“If it wasn’t for those boys, this whole neighborhood would have been burned and turned into hell,” said Fortunée Fitoussi, a cashier at Boulangerie Nathanya, a popular bakery in a large Jewish neighborhood of kosher grocery stores and blocky apartment buildings in Sarcelles often called Little Jerusalem.

But while some Jews embraced members of the group as heroes, it also added a volatile element to France’s sometimes violent street protests as the Gaza war fueled tensions, especially between Muslims and Jews, in a climate of growing anti-Semitism in France and elsewhere in Europe.