Police say they do not believe paramilitaries were behind trouble in east Belfast on Friday night.
Six officers were injured as missiles were thrown and vehicles were damaged following a "mini Twelfth" parade.
Officers fired plastic bullets and used a water cannon to disperse the crowd. Seven people have been arrested for riotous or disorderly behaviour.
The trouble was not as serious as rioting which broke out in the same area nearly two weeks ago.
Chief Inspector Mark McEwan said tensions in the area had been heightened since that rioting.
"The parade itself passed off peacefully," he said.
"There were a number of minor incidents, one assault in particular seemed to be the catalyst for more intense, spontaneous disorder. The disorder was not orchestrated."
Police said the rioting seen two weeks ago had been orchestrated by loyalist paramilitary group the UVF.
Friday night's trouble erupted in Castlereagh Street and Albertbridge Road.
Police moved in to prevent skirmishes between small groups of nationalists and loyalists on the Albertbridge Road, close to the Catholic enclave of Short Strand.
Larger crowds then gathered and the PSNI used Land Rovers as a barrier.
Loyalists threw stones and bottles at police in riot gear and at one stage water cannons were deployed as officers pushed the troublemakers back.
Ch Insp McEwan said police on the ground were in constant communication with community workers to try to calm the situation.
"Despite the best efforts of community workers in the loyalist community, there was an element within that crowd who were determined to carry out violent disorder and the police in Castlereagh Street became the focus of that attack," he said.
"I would appeal to the wider community to take a step back and reflect on what has happened and keep a cool head as we move forward over next couple of weeks."
None of the injuries sustained by police officers are said to be life-threatening.
BBC Ireland correspondent Mark Simpson said even after the trouble eventually stopped, a large police presence was required overnight to keep the peace.
Jim Wilson, a community worker on the loyalist side, said it was hard to convince some youths that disorderly behaviour was "not productive".
"Tensions have been pretty high, but we marshalled the parade last Sunday that went straight up the opposite side of the road as it did last night and there wasn't a stone thrown, there wasn't so much as a crossed word," he said.
"When you get big crowds it's harder to manage, and sometimes when people have drink in them the sensibility goes out the window.
"You try to talk to young lads who would reason with you in a normal state, but when they get a bit inebriated you become the devil and they become right in everything that they do."
Mr Wilson added that in the run-up to July 11 and 12, community workers on both the loyalist and republican sides, along with the PSNI, had to work together to ease tensions in the area.
Two weeks ago petrol bombs and other missiles were thrown at police over two nights.
Three shots were fired during the second night of disturbances. A photographer was shot in the leg in some of the worst rioting in the area for a decade.
Northern Ireland's First Minister Peter Robinson said he was prepared to get "directly involved" in attempts to resolve the trouble in his east Belfast constituency.