The BBC reported that Jason Kalen, who runs The Marlborough in Wiltshire, fitted a bar, pizza oven and a TV in the wooden structure.
Mr Kalen said: "It's disgusting. Less than a week before we're supposed to open saying it doesn't comply. It makes no sense."
"I built it to their [Wiltshire Council] specifications. I've got a breathable roof with a one inch gap around the outside, I've got double doors, I've got ventilation through the ground up. Then we get an email saying it's not permitted."
"It's the lack of timing. They should've sent this a month ago, it's just not fair."
Mr Kalen said having worked closely with the council to realise his project "to suddenly do this to us is outrageous. I'm livid."
Jess Gibbons, the council's director for communities and neighbourhood services, said guidance on outdoor hospitality was emailed to more than 800 alcohol licensed premises in Wiltshire on Monday night, following the government's confirmation on moving to step 2 of the roadmap on 12 April.
He added: "This guidance is not new - it is the same as the guidance issued previously, following the last re-opening just prior to Christmas which was covered by the "all tiers" regulations.
"It is based on the legal rules for smoking shelters in the smokefree legislation from 2007 which licensees will be very familiar with.
"We have now contacted Mr Kalen to find out more about his new structure and to work with him and offer advice on what he needs to do to ensure it meets planning and licensing regulations."