Twenty-nine police officers have been injured by fireworks, bricks and other missiles in another night of sectarian rioting in east Belfast.
Violence broke out between republicans and loyalists returning from a protest at Belfast City Hall over a council decision to restrict the flying of the Union flag there.
Northern Ireland's most senior police officer praised his "courageous" colleagues, adding that the vast majority of people were grateful for their efforts.
Senior politicians from Belfast, Dublin and London are to meet next week to discuss the protests after more than 40 days of road blocks and sporadic violence by loyalists failed to produce a solution. Stormont First Minister Peter Robinson and his deputy Martin McGuinness will join Northern Ireland Secretary Theresa Villiers and Ireland's Tanaiste (deputy leader) Eamon Gilmore.
Ms Villiers urged restraint. She said: "We can't afford to have these continuing protests damage our economy and destroy potential jobs for Northern Ireland's young people."
A second peace rally is to be held outside Belfast City Hall later.
Trouble erupted on Saturday afternoon on the Albertbridge Road near the nationalist Short Strand and police separated the opposing factions. As the loyalists approached the Short Strand there was violence across the interface with missiles being thrown by rival factions, which resulted in a number of properties being damaged in the Short Strand.
Police used water cannon and fired six baton rounds as they forced the two sides apart. Four officers were taken to hospital, two have been discharged.
Police Service of Northern Ireland chief constable Matt Baggott said: "This was a difficult operation dealing with a large number of people determined to cause disorder and violence. My colleagues brought the situation under control with exceptional courage and professionalism."
Mr Baggott added: "I know the vast majority of people will be grateful for their efforts. Police will continue to engage with all those committed to finding a solution to these issues."