PSNI Assistant Chief Constable Will Kerr appealed for calm as the Belfast protest over Union flag restrictions passed into the evening without major incident.
Earlier a driving school car was set alight in the east of the city and a policeman injured in a separate incident was taken to hospital. A 15-year-old youth and a 32-year-old man were arrested during the protest, police said.
ACC Kerr said: "Those involved in the protest should reflect on their own responsibility for any associated disorder and violence. I am appealing for calm as the day progresses. There have been too many nights of disorder across Northern Ireland and now is the time to move forward."