A utterly ignorant statement. Americans are those that inhabit the american continent. The americas are not limited to those who live in the United States. Like it or not, what you said has to be one of the stupidest statements I've ever read on this website.
Enough with this argument already. The term "American" has more than one meaning. The definitions from Merriam-Webster Online:
1 : an American Indian of No. America or So. America
2 : a native or inhabitant of No. America or So. America
3 : a citizen of the U.S.
4 : AMERICAN ENGLISH
Using the term in the more restrictive sense to refer only to those from the United States is perfectly acceptable.