At around 2.50am on June 24, the landlord was awoken by fire alarms at the Eastfield Arms on Bar Lane.
He discovered that a window had been broken and a bottle - believed to be filled with a fire accelerant - was alight on the floor.
The victim was able to extinguish the fire before it could take hold.
A spokesperson for South Yorkshire Police said: “Police attended the scene and an investigation has been launched to find those responsible.
“Officers are appealing for information which might help their enquiries.
“Were you in the area at the time? Did you see or hear anything suspicious?
“If you can help, please call 101 quoting incident number 113 of June 24.”