Chantana Pongkhawlou, 33, who was asleep with her partner in a back room at the Baan Tha Ruea Garden restaurant near the Thai Watsadu store on Thepkasattri Rd, was woken to flames at about 6am.
Ms Chantana and her partner fled to safety and promptly called the police, who arrived to find tables, chairs, the bar stereo and the thatch roof scorched by fire.
Police also found a plastic container with gasoline still in it on the ground at the scene and two used flame torches on the burned-out roof.
The damage to the venue was estimated at about B30,000.
Ms Chantana told police that the restaurant was busy most nights, which might have sparked jealousy among business rivals in the area.
“We bought the place, renovated it and only recently opened,” she said. “I have a lot of customers almost every night because we have live music – but we never have any problems with anyone.
“Maybe the owners of some of the restaurants around here are upset that our restaurant has been busy every night since we opened, and so they might have wanted to burn down our place to threaten us into closing our business.”
Police said they were treating the fire as a case of arson, and will question residents in the area in the hope of identifying the perpetrators.