Police say the UVF in east Belfast intends to “orchestrate and participate in serious disorder” on the Eleventh Night.
A statement was released by Assistant Chief Constable Alan Todd after police received information from the community.
It comes as detectives remain in the Cluan Place and Clandeboye Drive areas of the city, following reports of a loud bang earlier on Wednesday.
The remnants of what's believed to be a viable pipe bomb were found at Clandeboye Drive.
Meanwhile a bus has been set on fire in the Westwinds Estate, after being hijacked by a group of masked men with a suspected gun.
A number of passengers who were inside were not hurt, police said.
ACC Todd said: “Police have received information from the community which indicates that the East Belfast UVF intend to orchestrate and participate in serious disorder in East Belfast this evening directed against my officers.
“I would strongly urge people to desist from engaging in any violent or criminal behaviour.
“I would also appeal to those who have influence in this community to discourage people from taking part in any illegal activity.
“The safety of the public and my officers is of paramount importance and accordingly I will be reviewing my resourcing plans to ensure there is an appropriate and proportionate policing operation in place to deal with any disorder should it occur.”