US President George W. Bush claims Iran committed "a provocative act" in the Strait of Hormuz when Iranian "attack boats" approached and threatened three US navy ships.
"It's a dangerous situation and they should not have done it, pure and simple," Mr Bush told reporters at the White House. "I don't know what their thinking was but I'm telling you what I think it was."
The Strait of Hormuz, arguably the most prominent "choke point" in the global crude oil trade, handles 17 million barrels per day of global water-borne crude oil trade, over a third of total global shipments.
Iran has dismissed US concerns about the weekend incident, saying it was a routine contact.
"It was a provocative act," Mr Bush said when asked if he thought Tehran was trying to provoke a fight with the United States.
The incident was the latest sign of tension between Washington and Tehran, at odds over a range of issues from Iran's nuclear program to US allegations of Iranian support for terrorism and interference in Iraq.
The US navy believes the Iranian boats belonged to the country's Revolutionary Guard. In October, the United States designated the Revolutionary Guard Corps a proliferator of weapons of mass destruction and its elite Qods force as a supporter of terrorism.