Five cars were targeted last Friday night.
Three were completely burnt out and two others badly damaged.
Crime prevention officer at Henry Street Garda Station, Sgt Liam Sheehan, said two males were spotted near some of the scenes.
“One kept watch near the front gate leading to the house while the other moved to open the petrol cap,” he said.
He has called on post delivery staff to help them fight crime, particularly house break-ins.
“In the last couple of weeks we had a number of daytime break-ins, between 9am and 2pm, which is a vulnerable time as people have gone out to work, are taking children to school or may have gone out for a walk or gone shopping,” he said.
“It’s important that people keep a lookout for strange vans or cars calling to houses and report to the gardaí straight away anything that they are not happy about.
“I would also make a special appeal to all the post delivery personnel who are travelling all over the place between those vulnerable times. They are best placed to notice anything unusual and spot a vehicle that does not belong to the area or a particular person and, at times, I’m sure would probably know the types of cars people they are delivering post to, own.
“Post personnel in the past have been helpful to the gardaí in this regard and I would ask them to continue to do so and assist us in trying to prevent these daytime burglaries.”