The NZ Dental Association is urging Waititi to cut his ties with the sugary drinks manufacturer.
"I'd like to say you're an awesome director; my kids love you and I really enjoy all your movies [but] please can you cease all relationship you have with a company that is directly harming New Zealanders - particularly youth," Dr Beaglehole, a vocal activist for a sugar tax, added.
"When I saw it I felt so outraged - I feel really proud of him so I felt really conflicted."
Beaglehole says it is important to highlight the fact that "sugary drink companies, including Coca-Cola, are selling products that are harmful to New Zealanders and they need to be pulled up on that".
"What the Dental Association and many other organisations are calling on the Government to do is to show leadership, and implement evidence-based regulations that will reduce sugary-drink consumption," he added.