Chesterfield police are urging parents to keep tabs on their children - after reports of youngsters being abusive and volatile near the town’s library.
One 15-year-old girl recently spat at a security guard.
PCSO Adele Chapman-Jones said: "We've had a number of reports recently about the behaviour of some large groups of secondary school children, between the ages of 12 and 18, who are acting anti-socially, being abusive and volatile.
"Our team has also recently dealt with a 15-year-old girl who spat at a security guard. This kind of behaviour won't be tolerated.
"People should be able to visit, shop and work in our town without the worry of being subject to anti-social behaviour and we are working hard alongside partnership agencies to help ensure Chesterfield continues to be a safe place to be."
Officers are stepping up patrols in the area and may issue dispersal orders or take further action - including issuing community protection notices (CPN) - against anyone found to be persistently causing anti-social behaviour.
A CPNis aimed at preventing unreasonable behaviour which is having a negative impact on the local community's quality of life.
Breaching a CPN can result in a fine of £100, which a parent may be liable to pay.
PCSO Chapman-Jones added: "Parents may be able to help us prevent these issues by simply taking the time to find out where their child is, who they are with and what they are doing – and by making sure they understand what is anti-social and unacceptable behaviour."