I'm sure that in time the United States will respond to the latest Iranian rhetoric and saber rattling propaganda. The response will probably be a yawn, followed by "who cares" -- all couched in diplomatic language. Iran isn't stupid, they know they'd lose badly if they took the United States on in battle.
If there is one thing that the US can never, ever do, it's look weak in the face of a threat. I think that Iran war message is a really childish thing and that we shouldn't really give to much credence to it, but I think that the US will.
I do not believe the US will respond to Iran's "war message," because I don't believe it is a war message. Iran is simply pulling some of its Navy fleet into the Atlantic and coming close to some American interests. We have done comparable things to Iran and threatened worse, there should be no response to their current plans.
The US Navy will respond only if Iran actually sends warships close to our shores. At this point, the Navy hasn't detected any Iranian Navy ships steaming towards the Atlantic coast of the United States. The United States Navy shouldn't be messed with. Iran didn't threaten the United States because it's empty.
The United States has said Iran's threat to move warships close the America's maritime borders has not moved forward as of yet. Despite making overt threats to sink American vessels, no Iranian warships have made the move towards American waters as of yet. The United States shouldn't respond with anything unless the actual ships in the small fleet move towards the eastern seaboard. The American Navy isn't stupid, they will sink any Iranian ships that get close.