Two youths were arrested and e-scooters seized after gangs of children caused havoc in Lancaster venues.
One group of children harassed staff and other young people at a local youth group on Friday night, said police.
Later, another gang harassed staff in food venues in Lancaster city centre, shouting abuse at them and customers and throwing items around.
Police made the two arrests and confiscated three of the youths' e-scooters.
"Your local neighbourhood officers last night were kept busy with a minority of local children who think it is appropriate to cause antisocial behaviour towards others," said a post on the Lancaster Area Police Facebook page.
"One group last night thought it was acceptable to attend a local youth group and instead of join in, harassed the staff and the other children who were trying to enjoy the activities put on for them.
"Later on another group in the city centre thought it was appropriate to harass staff of local food venues, shouting abuse at them and their customers and throwing items around the venues.
"As a result two youths were arrested for their unacceptable behaviour in the city centre and taken into police custody.
"Furthermore three of the youths had their e-scooters taken off them to be destroyed.
"We know most children are nice and respectable and it is the small minority who ruin it.
"But please if you are a parent make sure you know where your children are and what they are doing."
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