The Pakistani police arrested more than 50 people in the city of Mirpur after hundreds gathered, shouted slogans against Israel, and set fire to a KFC shop.
Social Media footage shows protesters holding large signs with the inscription "Free Palestine" while shouting anti-Israeli slogans.
The protesters later stormed the KFC and set it on fire.
According to local police data, about 400 people participated at the peak of the protest and confronted the police forces.
Since the outbreak of the war, various Muslim countries have started boycotting KFC, McDonald's, and Starbucks chains perceived as pro-Israeli.
The boycott stems, among other things, from claims that the American chains themselves support Israel, but also against the backdrop of the protesters' anger at American support for Israel.
The Pakistani police said that the detainees are not identified with any specific organization, but some of them are associated with the Pakistani terrorist organization Tehreek-e-Labbaik.