The blaze at the bar did not appear to be motivated by any ill-will towards its owner, Hamlin said.
An armchair was also set alight in a driveway of a Cargill St property, and a pile of newspapers lit underneath a car in Cumberland St, between 3.30am and 4.05am.
A Fire Service spokesman said the blaze at Di Lusso Bar was noticed by a crew attending the Cumberland St fire.
Four appliances from Willowbank, Dunedin, St Kilda and Roslyn attended the Stuart St blaze and a fire investigator was at the scene this morning.
The Allbell Chambers building is more than 100 years old.