The attack happened in the Ardmonagh Parade area.
Detective Sergeant Conlan said: “We received the report of a fire just before 2.30am. Police attended along with colleagues from the Northern Ireland Ambulance Service and Northern Ireland Fire & Rescue Service.
“It is believed a sofa outside a house had been set on fire and this subsequently spread to the house itself. Thankfully, no one was inside at the time.
“Two houses – this one and the adjacent property – have been left badly damaged, while two other nearby properties have suffered extensive smoke damage.
“Enquiries are continuing and we are appealing to anyone with information, or who witnessed anything suspicious in the area, to contact police on 101, quoting reference number 152 of 01/08/19.
“Alternatively, information can be provided to the independent charity Crimestoppers on 0800 555 111, which is 100% anonymous and gives people the power to speak up and stop crime.”