The results of its survey have been revealed as retailers prepare for the change on Oct 1, which will see the minimum age for buying tobacco move from 16 to 18.
Association of Convenience Stores chief executive James Lowman said the government's internet-focused education campaign had been "woefully inadequate".
Lowman said: “This is a substantial change in the law that will lead to thousands of 16 to 18-year-olds and even more over-18s being asked for proof of age.
“The risk that low awareness presents is that people will blame the retailer for refusing to sell them a product they were previously able to buy. This will lead to flash points, abuse, intimidation and even violence.
“ACS has been helping retailers by providing advice and signage to display in store as a means of getting the message across to customers. Retailers can help themselves by being as clear as possible. This will go some way to averting the risk of abuse, intimidation and violence.”