No. The movie is being criticized because of the blatant racial divisions between the nations. For example, almost every Fire Nation citizen is Indian and the Earth Kingdom is mostly Asian. Then there is Katara, Sokka, and Kanna, the only Southern Water Tribe members (which is an Inuit inspired race), who are white. Theoretically, a tribe is generally made up of people who are, in some way or another, related by blood. Also, Avatar occurs in a world where Europeans either do not exist at all, or European colonization never happened. So other than being racist, this is completely incorrect.
Also, pointing out that Sokka, Katara, and Aang, the main protagonists, are white and almost nobody else is. It is not being called racist because there is not every race, it is racist because of its casting decisions of white people as the heroes and ethnic groups as the antagonists/background characters.