Wrong.
That flag represents states that wanted to secede from the Federal Union.
Does wanting to go your own way because you value state's rights over Federal collectivism make you an enemy? Apparently in your eyes it does.
Let's be honest, that war broke out because the southern states wanted to leave the collective (for various reasons, not just slavery) and Lincoln was having none of it. To say they were/are enemies of the United States is a misrepresentation of the reality of actual history.
Citizens of California have stated they want to secede from the United States as well. Should we go attack them? By your standards they are enemies, and unlike the confederacy, they are actually in the here and now.
en.wikipedia.org