The PSNI has said the attacks on journalists at a dissident republican commemoration in Creggan in Co Derry was “was extremely disappointing and completely unnecessary”.
The National Union of Journalists said reporters and photographers covering the event had been harassed and intimidated.
It is understood several were targeted with firecrackers and petrol bombs.
One photographer was warned not to return to the area and others were chased out.
Assistant Chief Constable Bobby Singleton said: “What we saw unfold in Creggan on Easter Monday, in particular the attacks on journalists, was extremely disappointing and completely unnecessary. We are supporting those affected and have commenced an investigation with a view to bringing those responsible to justice.
“What we saw yesterday was an unrepresentative, small minority who remain intent on causing violence and disorder and who will exploit local young people in the process.
“Moving forward, we’ll continue to focus on delivering policing with the community in Creggan.
“We welcome the broad condemnation of these events, and we are grateful for the wide support we’ve had from across the community since yesterday.”
NUJ Assistant General Secretary Seamus Dooley said the treatment of journalists was “completely unacceptable and deeply disturbing”.
A senior police commander said they had no doubt petrol bombs would have been used against officers if they had deployed to the area.
A van was set alight and motorists advised to avoid the area during disturbances which included very young children.
Several hundred people attended the parade, organised by the Derry 1916 Commemoration Committee, which started in the Central Drive area of Creggan, led by a masked colour party, to the City Cemetery for an Easter 1916 commemoration.
SDLP MLA Mark H Durkan is a Derry representative and a member of the policing board.
He said the community in Creggan had suffered at the hands of a small number of people intent on violence.
“What’s most distressing about the whole thing is that young people – children – were being encouraged, equipped and orchestrated to carry this out,” Mr Durkan said.
Sinn Féin MLA Ciara Ferguson said attacking journalists and burning a vehicle outside a community centre was “outrageous”.
“This reckless activity is not representative of the city,” Ms Ferguson said.
“Derry is a wonderful place, we must work together to create opportunities and continue the positive transformation.”
