Three police officers have been injured after trouble flared at the site of an anti-internment bonfire in north Belfast.
More than 150 officers were deployed after unrest earlier on Thursday.
Young people tried to push through police lines around the bonfire and fireworks, bottles and wood were also thrown.
Police later left the bonfire because of the “risks to innocent bystanders” posed by their presence.
Residents in nearby tower blocks have been told to leave their homes as the Housing Executive “cannot guarantee their safety” due to the proximity of the bonfire.
The PSNI said some of those trying to attack police lines were using women and children as human shields.
Assistant Chief Constable Alan Todd said this posed a dilemma for him as a police commander.
At a press conference on Thursday evening, he said: “I regrettably have had to take a decision today that the risks of continuing an operation to remove a bonfire were outweighed by the risks that operation would then pose to the wider community, the women and children, and others there present.”
“I have an objective to support our partners to clear a bonfire site in support of the local community’s wishes, but I also have a legal obligation to minimise any resort to use of force by police and to minimise the risks of so doing to public safety.”
The assistant chief constable said it was “a matter of regret that we weren’t successful in the objective of the operation”, but that it was “nonetheless a responsible, professional policing decision taken within the law and taken with very little room for other decisions to be made”.
He said although he did not regard the move “as a successful outcome”, it was made “in interests of the wider public safety, rather than continuing with an operation which might be seen to use force merely to prove a point and not achieve an objective”.
Six petrol bombs were recovered in the operation and a 13-year-old boy was arrested on suspicion of riotous and disorderly behaviour.
ACC Todd said those carrying out attacks on police were mostly youths who were being manipulated by older people, “probably related to violent dissident republican groupings”.
He added: “We will be reviewing CCTV footage to identify those who have been involved in the disorder, who can expect to be the subject of further police investigation and action.”
The Housing Executive has told residents in the nearby Oisin and Fianna tower blocks to leave their homes.
Sinn Féin MLA Gerry Kelly said: “This is a disgraceful situation because residents include people who are already vulnerable, some of whom have disabilities and other health related problems.”
He added that “the vast majority of the community have told [Sinn Féin] they do not want this bonfire” and that it had been built “by anti-social elements who torture this district throughout the year”.
Negotiations had been ongoing to persuade two young people to come down from the top of the bonfire so the removal could proceed.
After police left, a number of young people barricaded off Victoria Parade, the main road leading to the bonfire site.
Politicians from both Sinn Féin and the SDLP have previously raised concerns about the “unwanted” anti-internment bonfire.
Anti-internment bonfires are lit in some republican areas to commemorate the introduction of internment without trial of republican suspects, which was brought in by the British government on 9 August 1971.
The police said they had attended Queens Parade to “support contractors who have been tasked by the landowner to remove a bonfire from the road”.
In 2017, wood was removed from the bonfire over concerns it was too close to nearby buildings.
On Wednesday, SDLP councillor Paul McCusker called for the bonfire’s removal after it emerged that threatening graffiti had appeared on the wall of a nearby family centre.
The graffiti warnings, which are being investigated by police, stated “our wood goes, this centre goes” and “contractors beware”.
“There’s serious concerns about the level of threat here, there’s serious concerns about the level of criminality,” Mr McCusker told BBC Radio Ulster’s Stephen Nolan Show.
On Twitter, Sinn Féin MLA Carál Ní Chuilín said the “bonfire isn’t wanted” and that “all the criminal behaviour needs to be dealt with” by the police and statutory bodies.
“I’m not long back after visiting residents again and it’s clear the local families of those involved need to sit with the residents who are afraid and intimidated.”