"Hopefully China, France, Japan, South Korea, the UK and others affected by this artificial restriction will send ships to the area," Trump writes on the Truth Social platform.
Since the outbreak of war two weeks ago, Iran has attacked and threatened shipping traffic in the Strait of Hormuz - through which approximately a fifth of the world's oil production passes.
"Meanwhile, the United States will bomb the crap out of the coastline and continuously shoot Iranian boats and ships out of the water," the president continues.
The Truth Social post also contains a contradictory statement that the US has "destroyed 100 percent of Iran's military capacity", while saying it is still easy for Iran to strike the important waterway with drones, missiles and mines.
"One way or another," Trump wrote, "the strait will soon be open and safe."
Several in the family dead
In another post, Trump emphasizes that a joint effort to secure traffic through the Strait of Hormuz is necessary.
"This should always have been a team effort," he writes.
The statement comes after Trump previously criticized allied countries. A week ago, for example, he dismissed Britain's idea of sending aircraft carriers to the Middle East with "We don't need them anymore."
Israel's military states that the country's air force has carried out 400 waves of attacks against Iran so far in the war.
In Eyvan, in western Iran, six members of the same family were killed, the AP reports. One of the victims was a six-month-old infant.
Tensions are rising after the US's overnight attack on military targets on the Iranian island of Kharg - through which around 90 percent of Iran's oil exports pass.
Sources also told several American media outlets on Friday that the United States is sending a naval landing force to the region, consisting of at least one amphibious ship and up to 2,500 Marines.
Oil plant on fire
Iran continued to attack Israel and countries around the Persian Gulf on Saturday.
The US embassy in Baghdad, Iraq, has been damaged in an attack, and in Kuwait, drones are reported to have struck both the country's international airport and an air base.
Iran's state-controlled Fars news agency reports that 15 people were killed when a missile hit an industrial area in Isfahan, AFP reported.
An oil facility in the port of Fujairah in the United Arab Emirates is on fire after the wreckage of a downed drone fell on it.
