Police say children as young as 10 have been involved in throwing bricks at cars and stoning Metro buses in west Belfast.
The incidents happened in the area of the North Boundary Street junction with the Shankill Road at about 6.30pm on Sunday.
Two buses were stoned and services had to be pulled from the area for a time as a precaution.
“It’s concerning that young children, some of whom were believed to be around 10 years old, were involved in this incident,” PSNI Sergeant Bethel said.
“I’m appealing to those responsible to think of the potential consequences of such actions.
“It’s not just the follow-on disruption - you are risking the safety, even lives, of those on-board.”
Police are urging parents and guardians to know where their children are, who they are with, and what they are doing.
“We will continue to work alongside local representatives and partner agencies,” Sergeant Bethel added.
“But it is disappointing that some people continue to disregard our repeated warnings.”
Police are also appealing for witnesses or anyone with information to contact them on 101, online, or anonymously via Crimestoppers on 0800 555 111.