Authorities say the suspect forced his way into the spa in Flushing and attacked a 46-year-old woman.
The incident happened on Union Street around 4:30 p.m. Saturday.
The victim was taken to the hospital for treatment.
The suspect is described as a white male in his 40s, standing 6-feet to 6-foot-4 and weighing about 220 pounds. He was last seen wearing a light blue T-shirt, shorts, sneakers and a baseball cap.
Anyone with information in regards to this incident is asked to call the NYPD's Crime Stoppers Hotline at 800-577-TIPS.
