Officers were called to an address in Rivergreen, Clifton, at around 6.45pm on Sunday after the blaze was reported.
Several windows at the address were also smashed in what officers believe was a targeted attack.
Nobody was hurt and the fire was soon extinguished by Nottinghamshire Fire and Rescue Service.
Detective Sergeant Steve Dalby, of Nottinghamshire Police, said: “Our investigation is at an early stage and we are working to understand what happened in the moments before, during and after this incident.
“To this end we would like to hear from anyone who saw or heard anything suspicious in the area at around 6.45pm yesterday evening. We believe this to have been an isolated but officers have remained in the area to provide local reassurance.
“Anyone with information should call police on 101, quoting incident number 631 of 19 February 2023.”
