Seven PSNI officers sustained minor injuries when trouble flared after a loyalist band defied a ruling not to march past a Catholic church in Belfast.
The Young Conway Volunteers had been banned from parading past St Patrick's Church on Donegall Street after being filmed playing an allegedly sectarian song at the spot during 12 July parades.
A number of bands played music between Clifton Street and Unity Street area, which police also said was a breach.
A female officer was treated in hospital for a head injury but has since been released.
It is understood police were attacked when they attempted to keep nationalists opposed to the parade and loyalists apart.
Bottles were thrown from both sides during the trouble.
The Parades Commission imposed the restrictions, which were unsuccessfully challenged in the courts, on the band for the Royal Black Institution march.
Assistant Chief Constable Dave Jones, head of the policing operation, said anyone who defied the ruling will be pursued.