The chairman of the protection society, Dave Foreman, said the proposed store "looked like a warehouse" and had adverse effects "which are more than minor" in relation to the town's heritage, parking and traffic.
"One would have hoped the TCDC would have publicly notified the issue," said Mr Foreman.
"The principal aspect in the district plan when it comes to Coromandel with regards to heritage is the streetscape, whereas in Thames it's the buildings, and this proposal, given the small nature of the town, is a significant development in the main street."
Mr Foreman said 40 per cent of the shop's frontage appeared to be a blank wall and nearly 90 per cent of the Charles St side had no windows.
Star and Garter pub co-owner Karen McMillan said Four Square owner Foodstuffs should comply with heritage criteria and main street parking requirements.
"All we are asking is that they come on board with the township's vision of the colonial impression - not a big warehouse that is not in keeping with our heritage character."
Council development planning manager Mark White said Foodstuffs had to make the new store "look like a heritage building yet comply with modern-day standards".