Tehran, Iran - Iran's supreme leader Ayatollah Mojtaba Khamenei said in a written message on Thursday that the US had been defeated in its war with the Islamic republic, as the Iranian leadership defied President Donald Trump's warnings of a prolonged blockade.

"Today, two months after the largest military deployment and aggression by the world's bullies in the region, and the United States' disgraceful defeat in its plans, a new chapter is unfolding for the Persian Gulf and the Strait of Hormuz," the message read on state television said.

The message by Khamenei, who has yet to appear in public since his appointment on March 9 as Iran's new supreme leader, came on the annual national celebration of "Persian Gulf" day in Iran.

Mojtaba Khamenei became supreme leader after the US and Israel launched a massive campaign of strikes on Iran on February 28, killing his father and predecessor Ali Khamenei, as well as members of his immediate family.

Last week, the New York Times citing several unnamed Iranian officials said the younger Khamenei was "gravely wounded" in the strikes but has remained "mentally sharp."

In his Thursday message, he said US bases in the region "lack even the capacity to ensure their own security, let alone provide any hope of securing their allies."

He hailed what he called Iran's "new legal framework and management" of the strategic Strait of Hormuz, a key energy chokepoint, as a means to bring "comfort and progress" for countries in the region.

Last week, a senior lawmaker said Tehran has received the first revenue from tolls it imposed on the strait.

Khamenei predicted a bright future for the Gulf without the US and condemned "outsiders," saying those who interfere from thousands of miles away "have no place there except at the bottom of its waters".

He also lauded the people of Iran who he said "consider all national capacities – identity, spiritual, human, scientific, industrial, and advanced technologies from nano and bio to nuclear and missile – as their national capital".

Earlier Thursday, Iran's President Masoud Pezeshkian had said a US naval blockade imposed in retaliation against Iran's action in Hormuz was "doomed to fail".

Pezeshkian added that such measures would "not only fail to enhance regional security, but are in fact a source of tension and a disruption to lasting stability in the Persian Gulf".

Other figures have also struck a tone of defiance, with navy commander Shahram Irani signalling that Iran would deploy recently-developed naval weaponry against US troops in the region.