Three men were seen pouring the flammable liquid into four cars in St Clement Street, Aberdeen at about 2am on Monday, 24 May.
Two of the cars caught fire and the other two were also damaged in the incident.
Firefighters were called to the scene and extinguished the blaze shortly after the cars were seen on fire.
No one was injured in the incident.
Police are appealing for witnesses and are asking for anyone with further information about the vandalism attack to come forward.
Detective Sergeant John Pirie of CID at Queen Street Police Station said : “Three men were seen to exit a silver vehicle in the earlier hours of this morning and pour petrol into four cars in the street. Two of the cars caught fire but were quickly extinguished by Scottish Fire and Rescue Service. No one was hurt as a result.
“We are keen to trace the three men responsible and I would appeal to anyone who was in the area at the time to come forward. I would also appeal to anyone who has a ring door bell or CCTV to get in touch, you may have captured something that may assist our enquiry."
Anyone with any information is asked to contact Police Scotland through 101 quoting reference number 0204 of Monday, 24 May. Alternatively Crimestoppers can be contacted on 0800 555 111, where anonymity can be maintained.