Well, anime is defined as: a style of Japanese film and television animation, typically aimed at adults as well as children.
and avatar was made in America, so it cant be anime, as unfortunate as it is.

HOWEVER

Some people who like anime also enjoy it, and thats okay.

no, it's not anime. end of the story.
though it's storyline features some anime quality's
but this is america

dont catch me slippin up
dont catch me slippin up
Look what I'm whippin' now

dont catch me slippin up

don't catch me slippin up

Look what I'm whippin' now

This is America (woo)