All four people injured in the attack, including two police constables guarding the mosque, remained in hospital Sunday.
Residents said temple bells summoned dozens of men who stormed the mosque and started throwing stones and beating up worshippers.
Several homes in the area were also damaged, they said.
Seventy percent of Sri Lanka's 20 million population follow Buddhism, while Muslims are the second largest religious minority with just under 10 percent after Hindus who make up about 13 percent.
Others are Christian.
Police announced that a 13-hour curfew would be reimposed, starting at 6:00 pm (12:30 GMT) across the residential and commercial areas of Grandpass district, which remained under tight security following Saturday's attack that left four people wounded.
Witnesses reported scattered stone-throwing in the neighbourhood Sunday as authorities deployed more police and paramilitary commandos to keep the situation under control.
Soldiers armed with automatic rifles w