Iran signed UNCLOS 1982 which most countries signed: https://en.wikipedia.org/wiki/List_of_parties_to_the_United_Nations_Convention_on_the_Law_of_the_Sea https:

Iran signed UNCLOS 1982 which most countries signed: https://en.wikipedia.org/wiki/List_of_parties_to_the_United_Nations_Convention_on_the_Law_of_the_Sea https://en.wikipedia.org/wiki/List_of_parties_to_the_United_... in which Iran stated that only parties that signed are entitled to free passage through its maritime territory, except for warships etc. This was accepted by all. The US did not sign.