This policy does not recognise Taiwan's independence and claims that it is part of China.
After getting the review removed from Google, the cafe has since received eight more one-star reviews with no mention of the food or service.
They all come from new accounts and do not respond to requests to elaborate on any issues.
Park said he would continue to display the flag on his menu.
He said it was a shock to see the backlash.
"First of all, our cafe serves a variety of culturally inspired menus. Our decision was made to satisfy our multicultural customer range in Auckland.
"During our process of finding menu ideas, we came across the Taiwan Sandwich. Small flags were added to the menu in purpose to help identify each sandwich.
"We simply Googled Taiwan and added the flag that was shown. This did not have any relation to the perspective of 'one China'.
"Receiving multiple one-star ratings on our Google review due to using the Taiwan flag had us in shock, as we did not have any attempt to offend any of our customers," Park said.
Restaurant Association chief executive Marisa Bidois said fake reviews can be a real issue for hospitality owners and can be very damaging.
Bidois encourages business owners to contact the review sites where they feel they have been unfairly judged.
"The industry is facing an extremely tough time and issues like these add to an already stressful situation."
She said the majority of Kiwi consumers are savvy enough to spot a fake online review.
Director general of the Taipei Economic and Cultural Office Kendra Yung-Shao Chen said Taiwan is a sovereign nation and is not subordinate to the People's Republic of China.
"The PRC government has never ruled Taiwan for a single day and definitely has no right to claim or to represent Taiwan or dwarf the name and flag of Taiwan.
"China has been exerting undue pressure in the international community. Now even delicious sandwiches are not spared."
- RNZ
