More than 100 motorcycles have been stolen in the CBD since the start of the year.
Police currently want to speak with two men, who have been seen loading motorcycles into the back of a white van.
Police say most of the thefts have taken place at night and have occurred both from the street and from secure parking.
According to police, thefts of motorcycles have also increased across Docklands, East Melbourne and North Melbourne.
Police have asked CBD locals to keep an eye out for people loitering or behaving suspiciously in apartment car parks.
They also ask people to keep a look out for suspicious activity and to take down registration numbers if you notice suspicious behaviour.
Residents and workers who observe suspicious behaviour around motorcycles should contact Crimestoppers or call 000.