Surveillance video from the October 6th attack along North Watts Street was released Wednesday.
In the video, the suspects are seen shoving one of the 18-year-old girls to the ground and took her purse.
They tried to take the other victim's cell phone, but she held onto it.
Investigators believe the robbers are about 20 years old.
Anyone with information is urged to contact Philadelphia Police at 215-686-TIPS (8477), text a tip to PPD TIP (773847) or through PhillyPolice.com.