MAp Distance Iran to US
It's extremely complicated...
US Central Command is very unhappy about an "unprofessional interaction" that the guided-missile destroyer USS Mahan had with an Islamic Revolutionary Guard Corps Navy vessel in the "Arabian Gulf" (known by normal people as the "Persian Gulf") on April 24.

What happened? And why is CENTCOM afraid of using the word "Persian"?

According to the Americans:
Unprofessional Interaction between IRGCN vessel and USS Mahan in the Arabian Gulf

The Iranian vessel came within 1,100 yards of Mahan, closing the distance despite Mahan maneuvering to open the distance between the two vessels.

[...]

Naval Forces Central Command does not assess this interaction as unsafe in any way; however, it doesn't meet the standards of professional maritime behavior due to the Iranian vessel closing the distance to the US ship in violation of the maritime "rules of the road."
Okay, but imagine if Iranian vessels were chilling off the coast of Martha's Vineyard — in international waters, of course. We doubt that CNN would be concerned about US Navy ships not abiding by the "rules of the road".

Quite the contrary. Wolf Blitzer would self-destruct.

At any rate, Iran's Foreign Minister Javad Zarif found a very polite way of responding to allegations of Iranian rudeness:

Breaking: Our Navy operates in —yes, correct— the Persian Gulf, not the Gulf of Mexico. Question is what US Navy doing 7,500 miles from home
One major problem with this argument: It's way too logical.