Fire crews responded to a 911 call early Saturday morning about smoke and flames emerging from a building at 2 Robinson Avenue.
The fire was in a vacant building, and no injuries were reported.
The building is the former home of the Iranian Culture Centre.
The call came in just before 4 a.m., and fire crews were still on the scene at 5:40 a.m.
The extent of the damage is still unknown, and the cause of the fire is under investigation.
Ottawa police said the incident is not being treated as suspicious.