A 13-year-old boy is among eight people arrested in connection with riots on the streets of Belfast.
Police said 15 officers were injured on Friday night after being targeted by a crowd of mainly young people in Sandy Row, throwing stones, fireworks, flares, manhole covers and petrol bombs.
The PSNI’s Belfast District Commander, Chief Superintendent Simon Walls, said “a small local protest quickly developed into an attack on police officers” and that at points there were up to 300 people of all ages on the streets.
He called for calm, urging anyone with influence in the loyalist community to dissuade young people from causing violence and harm.
He said: “I’m not going to enter into dialogue about political commentary.
“What I would ask is that people with influence, people in local communities, would dissuade young people, or anyone else, intent on causing violence or intent on harming police officers.”
He described it as a “real tragedy” that children as young as 13 and 14 were among those arrested.
“I think it’s a tragedy that any child in Northern Ireland is sitting in a custody suite this morning and facing criminal investigation, possibility of being charged and possibility of facing a criminal conviction,” he said.
“It shouldn’t happen. And that’s why I’m very keen that people with influence try to ask anyone intent on violence to please step back. It’s not the way to resolve tensions or arguments.”
Political leaders have also called for calm over the Easter weekend following the riots.
Stormont’s First Minister Arlene Foster urged young people “not to get drawn into disorder”, saying violence “will not make things better”.
The DUP leader said: “I know that many of our young people are hugely frustrated by the events of this last week but causing injury to police officers will not make things better.
“And I send my strong support to all of the rank-and-file police officers that are on duty over this Easter weekend.
“I appeal to our young people not to get drawn into disorder which will lead to them having criminal convictions and blighting their own lives.
“I also ask parents to play their part and be proactive in protecting their young adults.”
Mr Lewis said: “Violence is never the answer. There is no place for it in society.
“It is unwanted, unwarranted and I fully support the PSNI appeal for calm.”
He added that his thoughts were with the officers injured.
The trouble came after four successive nights of disturbances in the unionist Waterside area of Londonderry.
Loyalists and unionists are angry about post-Brexit trading arrangements which they claim have created barriers between Northern Ireland and the rest of the UK.
Tensions ramped up further this week following a controversial decision not to prosecute 24 Sinn Fein politicians for attending a large-scale republican funeral during Covid-19 restrictions.
All the main unionist parties have demanded the resignation of PSNI Chief Constable Simon Byrne, claiming he has lost the confidence of their community.
The Sandy Row disturbances have been met with widespread political condemnation.
Ulster Unionist Policing Board member Mike Nesbitt said the riot “did not just happen” and people were encouraged to take part.
“Someone planned it, someone encouraged people on to the streets,” he said.
“I challenge them to explain a strategy that portrays loyalists and unionists as law-breakers, prepared to attack the PSNI, injure officers and frankly take the focus off Sinn Fein and the republican movement.
“The history of street violence is unambiguous. It does nothing to advance our cause.
“It is a huge mistake and should not be repeated.”
Alliance South Belfast MLA Paula Bradshaw said responsible leadership is required from all quarters to stop a repeat of the scenes in Sandy Row.
Ms Bradshaw said those involved in the rioting had “achieved nothing other than bringing misery upon their own area”.
“There is no future in this type of behaviour,” she said.
“Our thoughts must also be with the police officers who were injured. Public servants have a fundamental right to go to and return from work without being targets.
“I trust therefore those in positions of political leadership and responsibility will reflect on whether their words and actions in recent days have helped or hindered when it comes to reducing tensions.
“Political leadership requires the right decisions, not the easy ones. It often means taking people to places where they are uncomfortable for the sake of the greater good.
“We are seeing very little of that currently and it is resulting in serious harm.”