WASHINGTON -- US President Donald Trump on Thursday threatened Iran to stop charging fees to tankers passing through the Strait of Hormuz if the country is doing so.

"There are reports that Iran is charging fees to tankers going through the Hormuz Strait -- They better not be and, if they are, they better stop now!" Trump wrote on his social media platform Truth Social.

A day earlier, Trump told ABC News he is weighing to set up a "joint venture" with Iran to charge tolls from vessels passing through the crucial waterway through which about 20 percent of global oil is transported, calling it "a beautiful thing."

He also said on social media on Wednesday that "big money" could be made by the US "helping with the traffic buildup in the Strait of Hormuz."

Iran demands oil tankers pay a transit toll of 1 US dollar per barrel for passing through the strait, according to a report from The Wall Street Journal on Thursday.

Marine traffic in the strait remained at a trickle. For the first time since the ceasefire was reached on Tuesday, two non-Iranian oil tankers were tracked crossing the strait, The New York Times reported on Thursday, citing ship-tracking firm Kpler.