There are many Americans who are truly anti war, or anti Iraq war or just anti Bush, and they protest and demonstrate accordingly. Nothing in the world wrong with that.
On the other hand, and as this artile and link point out, there are those who claim to be anti war, and anti Iraq war, who are niether. To be a pacifist is one thing, to actively support the other side is completely different. That is not "anit war" that is Pro War.
Unfortunately for the true pacifist, or truly anti Iraq war, most Americans don't seperate those who consider the bacteria in Iraq the "Freedom Fighters" from the rest... and the anti American ones prefer it that way.