Bricks were thrown at three occupied caravans at Kiln Park, Tenby, on Saturday evening.
The bricks narrowly missed the windows. However, police say if they hadn't, the incident, which occurred at approximately 5.30 pm, could have resulted in serious injuries to those inside.
A witness reports that four youths were seen running from the area.
Anyone with information is asked to contact PC1045 Alex Jones at the town's police station on 0845 330 2000 or Crimestoppers on 0800 555 111.