Nine police officers were injured and up to ten shots were fired at police after trouble flared overnight in north Belfast, - BBC reported.
It followed a Protestant Orange Order parade in the Catholic Ardoyne area of north Belfast, police have said.
No-one was injured as a result of the gunshots on Thursday. Petrol bombs and bricks were thrown at police lines by both nationalists and loyalists.
Police fired six plastic bullets. Two people were arrested. - "1TV"
Police also used water cannon on the crowds.
In Londonderry, petrol bombs were thrown in the Westland Street area and at the city's walls. Cars were set alight in Fahan Street.
DUP MP for north Belfast Nigel Dodds condemned the decision by the Parades Commission to allow a nationalist protest parade to take place in north Belfast.
"I blame entirely the Parades Commission who permitted this parade by a dissident republican crowd intent on trouble," he said.
"People here in Twaddell and the Orange Order and others have tried their very best to act in the best way possibly, responsibly. But when that parade came out,they were faced with incredible abuse and violence aimed at them. Of course there were people who retaliated and I regret that."
During the violence in north Belfast, three cars were hijacked and two of them pushed at police. At least one of them had been set alight.