Pro-Palestinian protesters clash with police in Paris
A Reuters photographer said demonstrators in northern Paris launched projectiles at riot police, who responded by firing teargas canisters and stun grenades.
Demonstrators also climbed on top of a building and burned an Israeli flag. At least one car was set on fire.
A police spokesman said that 38 demonstrators had been arrested by early evening and that the clashes were dying down.
However, dozens of police trucks were seen rolling into the narrow streets of the historically Jewish Marais neighborhood where French media said groups of protesters had assembled.
President Francois Hollande earlier said he had asked his interior minister to ban protests that could turn violent after demonstrators marched on two synagogues in Paris last weekend and clashed with riot police.
"That's why I asked the interior minister, after an investigation, to ensure that such protests would not take place," he told journalists during a visit to Chad.
Foreign Minister Laurent Fabius responded to criticism France was biased in favor of Israel, which sent ground forces in on Thursday after 10 days of air and naval barrages failed to stop rocket fire from Gaza.
In London, thousands of pro-Palestinian demonstrators marched peacefully clutching Palestinian flags and banners reading "Stop the bombing" and "Free Palestine" before congregating outside of the Israeli embassy.