The United States has added the Persian Gulf Strait Authority to its sanctions list, according to the Treasury Department's website.
The body was established by Iran to manage requests for passage through the Strait of Hormuz.
The strait handles about a fifth of the global oil supply. Tehran's control has disrupted the world economy.
Iran closed the strait after the U.S. and Israel launched an attack on February 28.
Last week, the Authority published a map claiming large areas on both sides of the chokepoint.
The designation was announced by the Office of Foreign Assets Control.
