On Friday, the police in Malmo reported that demonstrators at a protest against Israel had shouted threats of violence against Jews. Later, two firebombs were thrown at a Jewish chapel in Malmo. The police are investigating the episode as a possible hate crime, Radio Sweden reported Monday, citing the TT News Agency.

“This is totally unacceptable in Sweden,” Mr. Lofven said. “There must not be any room for this hatred toward Jews. We must tackle this from all angles to extinguish it. Anything we can find we must report. We need to get it out in the open and to see to it that people are brought to justice.”

Mr. Lofven on Monday told the newspaper Aftonbladet that Jews were under assault from both the extreme right and the far left. He also expressed concern about what he said was rising anti-Semitism among immigrants from the Middle East.

“That goes against the very moral fiber of Sweden,” he told Aftonbladet. “Here all people have the same value.”