The initiative, called 'Operation Hyena', asks retailers to ban the sale of alcohol to under-21s on a Friday and Saturday night from 5pm to 10pm for the next two months.
The move comes just weeks after the Scottish government launched a consultation on measures to deal with alcohol misuse, including a proposal to increase the legal purchasing age for alcohol to 21 in the off trade.
SGF chief executive John Drummond said: "I believe it is quite wrong for any constabulary to introduce the same measure, albeit on a limited basis, while this consultation is in place.
"We take the issue of age-related sales seriously but we feel that operations of the kind suggested only serve to confuse staff and customers while discriminating against the majority of 18- to 21-year-olds who drink responsibly.
"We are happy to co-operate with the police and other authorities within the parameters of the law, and we can share CCTV information and intelligence on suspicions around third-party/proxy purchases.
"However, we are not happy at entering into a scheme which has not been well publicised and has been communicated to the trade at very short notice."