Filmmakers using animals like to feature the AHA's stamp of approval during the end credits of movies to assure cinemagoers the creatures weren't harmed or abused in any way during the making of the project.
But Todd Phillips decided he didn't need the organization's OK, even though a capuchin monkey features heavily in the new comedy.
AHA officials tell Entertainment Weekly they offered to visit the set in Thailand, but were turned down.
It now appears the director could have used their help after upsetting animal rights groups by joking his monkey was taught to smoke for the film, "The Hangover Part II".
Phillips has since backtracked and executives at Warner Brothers have assured film fans and creature lovers alike the ape never held a lit cigarette, adding that smoke was digitally added.
But that's not enough for activists animal rights group People for the Ethical Treatment of Animals - they are upset a monkey was used in the film at all.
In a letter to Phillips and the film's producers, PETA president Ingrid Newkirk writes, "The use of exotic animals is of grave concern to us."