Paris’ police chief authorized the march from République to Nation, two large plazas in eastern Paris, but vowed that any behavior deemed antisemitic or sympathetic to terrorism would not be tolerated.

Multiple countries in Europe have reported increasing antisemitic attacks and incidents since Oct. 7.

In an attack Saturday, an assailant knocked on the door of a Jewish woman in the French city of Lyon and, when she opened, said “Hello” before stabbing her twice in the stomach, according to the woman’s lawyer, Stéphane Drai, who spoke to broadcaster BFM. He said police also found a swastika on the woman’s door. The woman was being treated in a hospital and her life was not in danger, the lawyer said.

At the London rally, the Metropolitan Police said its officers made 11 arrests, including one on a terrorism charge for displaying a placard that could incite hatred. The police force had forewarned that it would also monitor social media and use facial recognition to spot criminal behavior.

On Friday, two women who attended a pro-Palestinian march three weeks ago were charged under the U.K.’s Terrorism Act for displaying images on their clothing of paragliders. In its Oct. 7 surprise attack on Israel, Hamas employed paragliders to get some fighters across the border between Gaza and southern Israel. Prosecutors said the images aroused suspicion they were supporters of Hamas, which U.K. authorities regard as a terrorist group.

In Berlin, around 1,000 police officers were deployed to ensure order after previous pro-Palestinian protests turned violent. German news agency dpa reported that about 6,000 protesters marched through the center of the German capital. Police banned any kind of public or written statements that are antisemitic, anti-Israeli or glorify violence or terror. Several thousand protesters also marched through the west German city of Duesseldorf.

In Romania’s capital, hundreds gathered in central Bucharest, many waving Palestinian flags and chanting “Save the children from Gaza.”

At a rally by several thousand people in Milan, Matteo Salvini, a deputy prime minister, spoke out against antisemitism, calling it “a cancer, a virulent plague, something disgusting.’’

In another part of Milan, a pro-Palestinian rally drew about 4,000 people and there was also a march by several thousand in Rome. Yara Abushab, a 22-year-old medical student from Gaza University, who has been in Italy since Oct. 1, was among the participants and described Oct. 7 as a watershed for her.

“They bombed my university, my hospital. I lost a lot of loved ones and right now the last time I heard something from my family was a week ago,” she said. “The situation is indescribable.”