Police officers and members of the public came under attack with bottles and petrol bombs in Londonderry on Monday night.
The police were dealing with disorder in the Lecky Road area near the site of a controversial bonfire.
Supt Gordon McCalmont said that people who were on the city walls were attacked with bottles and rocks.
A police officer was struck by a missile but was not seriously injured.
Police, who were sent out to prevent further disorder, were attacked with petrol bombs and other missiles.
Supt McCalmont said this type of behaviour could not be tolerated.
"Tonight will see the lighting of the bonfire and I would appeal to those in the community to use their influence to control the situation," he said.
Ch Insp Paul McCracken has appealed for calm.
"From a community perspective there was between 40 and 50 people there last night," he said.
"We are investigating reports that some people were using masks.
"We had sufficient numbers of resources to deal with the circumstances last night. We had forty to fifty officers as well."
A woman who lives in the Bogside has said she feels intimidated.
"We just don't need it. It is just really frightening."
Sinn Féin councillor Patricia Logue condemned the disorder.
"The community don't want this and it is very dangerous behaviour," she said.
Bonfires are traditionally lit on 15 August in some nationalist areas to mark the Feast of the Assumption.
In recent years, efforts have been made to replace the bonfire with family fun days and live music.
The bottom of the Lecky Road flyover in the Bogside was partially blocked last August by a 20ft-high bonfire.
On Monday afternoon, the Housing Executive installed protective fencing beside houses in the Bogside ahead of the bonfire being lit.
It made the move at the request of Derry City and Strabane District Council.
A spokesperson for the council said that they are working alongside a range of statutory partners to monitor the situation and ensure the safety of the general public.
A group who say they represent some of the young people building the bonfire, Junior McDaid House, have said that Monday night's trouble was "political policing".
Supt Gordon McCalmont said: "The PSNI rejects any suggestion of so-called 'political policing'.
"Officers were deployed last night in response to concerns expressed by local people witnessing instances of disorder."
Efforts by community workers to encourage people to attend an alternative event at the Gasyard Feile broke down last week.