At about 9.30pm on May 2, two males entered Best Wine and Food on Eastney Road while a third male believed to be with them waited outside.
One member of staff and a member of the public were assaulted before the two males that entered the shop went behind the counter and stole cigarettes, vapes, and money.
Witnesses described the two males who entered the shop as white and aged between 14 and 17 years old.
One had mousy coloured hair and was wearing a black hooded jumper, cream jogging bottoms and red and black trainers. The other had brown hair and was wearing black Nike shorts, white trainers and a dark long-sleeved Nike t-shirt.
Following initial investigations police are appealing for any further witnesses to come forward. Police would also like to speak to the member of the public who was assaulted.
Anyone with information should call 101 quoting reference 44230172507.