"All Iranian airlines will be shut down around the world," US Treasury Secretary Scott Bessent told the US broadcaster CNBC on Monday.
The measure is set to effect place on Wednesday, aiming primarily to put pressure on third countries.
"If they land, you cannot provide them with fuel, you cannot provide them with landing services, you cannot sell them tickets, or you will be knocked out of the (US) dollar system," he added.
Almost two weeks ago, the US imposed new and comprehensive sanctions on the Iranian aviation sector, including 27 airlines.
Foreign companies and banks also face consequences if they continue to do business with the affected airlines.
Bessent said the US government has held behind-the-scenes talks about further isolating the Iranian aviation sector, adding that China has shown itself to be co-operative in this regard.
Chinese President Xi Jinping is expected in Washington DC on Wednesday.
Last Wednesday Mahan Air, Iran's leading and most modern private airline, announced that it would no longer fly to Turkey or Oman.
The airline did not give an official reason.
A spokesman for Iran's Islamic Revolutionary Guard Corps, Hossein Mohebbi, said on Monday that "the war is not over" and warned that Iran would change its weapons, military tactics and targets if the conflict with the US escalates.
"We will certainly change the geography of the war," Mohebbi said in a statement carried by Iranian state media.
"We will certainly bring new weapons with new capabilities into the battle."
He said the Guard had prepared for a long-term war.
"Our targets will no longer necessarily be the same as before," he said, according to the Islamic Republic of Iran Broadcasting, adding that Iran has targets that have not yet been struck.
The more than six-month war began with US and Israeli strikes on Iran on February 28.
The conflict has included repeated attacks and efforts to negotiate an end to the fighting, with no agreement reached to reopen the Strait of Hormuz or revive talks over Iran's nuclear program.
The United Kingdom Maritime Trade Operations Centre (UKMTO) said on Monday a tanker was struck by an "unknown projectile" as it headed into the Strait of Hormuz.
Two crew members sustained minor injuries.
The UKMTO said the vessel is reportedly continuing to its next port of call under its own power.
Iran has asserted control over much of the Strait of Hormuz since February.
In peacetime, about 20 million barrels - roughly a fifth of the world's oil supply - passed through the strait each day.
Some tankers are again traversing the strait but traffic is well below what it once was.
with DPA
