Toronto police say the woman had just got off a streetcar, near Yonge and Dundas streets, when she was approached by a man at about 2 p.m. ET on Saturday.
Police say the woman was attacked by the man when she was on an elevator at nearby Dundas Square.
The man involved in the attack fled the scene.
Police say the suspect is a 40- to 60-year-old male, who is between 5'6" and 5'8" in height.