The incident happened at a Mobil Gas Station Mart on 8th Avenue in Greenwich Village just before 2 a.m. Monday.
Authorities say the man walked into the store, stole a pack of cigarettes and walked out. When a worker tried to follow him, the man stabbed him in the hand.
The 18-year-old worker needed stitches, but is expected to be OK.
The suspect is described as a white male, approximately 35 years old, standing 5-foot-10 and weighing 200 pounds.
Anyone with information in regards to this incident is asked to call the NYPD's Crime Stoppers Hotline at 800-577-TIPS.