I think you're very focused on finding reasons the blockade isn't one, to the point of some severe contortions. I'm not sure why you think the US is leery of acts of war; we've committed a bunch in the last year, including multiple preemptive decapatation strikes of world leaders.
You think it's an embargo; I (and much of the world) think it's a blockade. Whoever's right, this'd be deeply shitty antisocial behavior if you did it to your neighbor, and likely to lead to blows.