Protesters set multiple fires, including a bus ablaze, in Belfast on Tuesday the night after a stabbing which sparked anti-immigration demonstrators because the suspect is an asylum-seeker.
Aerial footage from British broadcaster Sky showed police seeking to disperse people in the Northern Irish capital. Other street fires appeared to be in residential areas of the city.
A Sudanese man has been accused over Monday night's knife attack where the victim, a man in his 40s, was taken to the hospital with serious injuries to his eyes, face and back.
Northern Ireland's leaders and chief constable had held a news conference earlier on Tuesday urging people not to incite hate and fear or target particular communities after media reported that protests were planned in response to the incident.
The suspect, 30, who was not named, was held in custody and charged with attempted murder, possession of a knife in a public place and making threats to kill.