Windows were broken in two vehicles parked at Old Castle Archdale in Fermanagh.
The incident happened sometime between 2pm and 4pm on Sunday (20 Nov).
Enniskillen police would like to hear from anyone who noticed any suspicious behaviour around the car park.
Nothing was stolen on this occasion, but there have been previous thefts from vehicles in the area.
Police are reminding people to keep all valuables out of view.
The warning comes after thieves targeted vehicles parked at churches in the county.