It happened at 10:30 p.m. Thursday night inside the restaurant located on the 2900 block of North Broad Street.
Police say a 19-year-old female employee was in the back of the store when she heard the doorbell ring.
As she arrived to the front of the store, the suspect approached her at the counter, armed with a handgun, and demanding cash from the register.
Click here to watch the surveillance video
The gunman got away with an unknown amount of cash before fleeing the store in an unknown direction.
Police describe the suspect as a black male, 20 to 30-years-old with a thin build and clean shave. He was wearing sunglasses, all dark clothing and armed with a handgun.
Anyone with information is asked to call police at 215.686.TIPS (8477) or text a tip to PPD TIP (773847).
You can also submit an anonymous tip online at PhillyPolice.com.