Police say a man has pretended to be a client to make contact with victims.
It is alleged that the man has then sexually assaulted these victims and stolen their personal property.
A police news release says the victims being targeted are of Chinese descent.
These incidents have been reported with "increasing frequency," police say, in the Yonge Street and Finch Avenue area, as well as the Yonge Street and Sheppard Avenue area.
The suspect is described as a black male who has worn a dark-coloured hat with light-coloured patterns on it. He has worn a puffy, dark-coloured jacket with light-coloured patches on its shoulders and he has carried a camouflage backpack.
Anyone with information is asked to contact investigators at 416-808-7474. Information can also be passed on anonymously to police through Crime Stoppers (416-222-8477).