Iran's newly appointed Basij paramilitary chief said Thursday that the Strait of Hormuz was under Iran's "control and management", a day after US President Donald Trump said the United States had "total control" of the strategic waterway.

Hossein Taeb said the United States had sought to undermine Iran's popularity in the region by launching another war over the Strait of Hormuz, but had again been defeated despite claims that Iran had neither an air force nor a navy.

"Today you see that the Strait of Hormuz is under the management and control of the Islamic Republic," Taeb said, according to the semi-official Fars news agency. He added that Iran was continuing its course in complete security.

The strait has been effectively closed by Tehran since the war began with US-Israeli strikes on Iran on February 28. Before the conflict, about a fifth of the world's oil and liquefied natural gas shipments passed through the waterway.

The United States subsequently imposed a naval blockade on Iranian shipping and ports while saying it would protect freedom of navigation for vessels traveling to and from non-Iranian ports.

In June, Iran and the United States reached an interim agreement declaring a permanent ceasefire and calling for a swift return to freedom of navigation in the Gulf.

The agreement unraveled weeks later after Iran resumed limited attacks on vessels it said were violating the terms of the deal. The United States then restarted strikes on Iran's southern provinces, saying the attacks were aimed at reducing Tehran's ability to target vessels in the Gulf.

Separately on Thursday, senior military and political official Rasoul Sanaei-Rad said Iran would not reopen the Strait of Hormuz unless the other side fulfilled its commitments under the interim agreement.

He said reopening the waterway was not something the United States could achieve unilaterally, according to Fars.

Sanaei-Rad also warned that Iran would respond more forcefully in any future conflict.

"In a possible future war, we will stand more firmly and more offensively," he said.