The newly-refurbished bus shelter at Coxhill, Narberth, has been damaged.
A small fire was lit within the confines of the shelter and discarded alcohol bottles were discovered there over the weekend.
The matter has been reported to the police who are anxious to speak to any witnesses.
"Apart from the obvious concerns regarding public safety of lighting an unprotected fire within the confines of the building, the resulting scorching caused to the walls amounts to damage, which the police take a serious view on," said PC Chris Rowe, of the town's police station.
"It is a disappointing development as the bus shelter was recently refurbished," he added. "Efforts are being made to identify the offenders and to this end Narberth police are appealing for information."
The town's county councillor, Wynne Evans, has been to visit the shelter and was 'appalled' to see the damage.
"I ask anyone who witnessed anything to contact Narberth police station," he said. Narberth police can be contacted on 0845 330 2000.