It happened at the McColls store in Spring Gardens earlier in June.
Detectives investigating an altercation in a convenience store in Buxton are appealing for a witness to the incident to come forward.
Police were called to reports of an altercation between two men in the McColls store in Spring Gardens, Buxton at around 7.30pm on Saturday, June 15.
The victim of the assault received minor injuries.
In the store at the time was a man who officers are keen to speak to. He intervened during the altercation and led the perpetrator out of the store.
The man is described as shaven headed and wearing a t-shirt.
Officers are keen to hear from the man as a witness to the incident and ask him, or anyone who may know him, to contact Derbyshire police using the below methods.