Police in Bargoed and Rhymney seized five off-road bikes during a recent one-day operation.
Officers teamed up with rangers from Caerphilly County Borough Council to target Gelligaer, Brithdir and Rhymney commons.
They seized three off-road motorbikes and two quad bikes that were being ridden illegally in the area.
Three riders received formal warnings and officers also issued four Antisocial Behaviour Order referrals. One rider has been summonsed to court for riding on the highway without tax
PCSO Neville Davies, from the Baroged Neighbourhood Policing Team, said: “Sadly, every Christmas we find parents purchasing off-road vehicles for their children often without giving sufficient thought to or understanding where they can be legally ridden.
“These operations with our partner agencies aim to tackle the antisocial use of off-road vehicles both on the commons and in residential areas.
“We often find that riders are not only breaking the law, but posing a serious risk to themselves, walkers on the common as well as the wildlife.
“This sends out a clear message that Gwent Police and our partner agencies will not tolerate such behaviour and are committed to ensuring that the quality of life for residents and legitimate users of the commons is not affected.”
To report incidents of illegal off-road riding, please contact Gwent Police on 101.