Iran has argued that US President Donald Trump breached a 1955 treaty with his decision to reimpose the sanctions after withdrawing from a multilateral nuclear accord.

But US State Department lawyer Jennifer Newstead told the court in The Hague that it "lacks prima facie jurisdiction to hear Iran's claims".

But Newstead argued that the United States had the right to protect its national security and other interests.

The treaty "cannot therefore provide a basis for this court's jurisdiction" in the case, she said.

The United States and several other world powers lifted sanctions on Iran under a 2015 accord after years of diplomacy. In return, Tehran made commitments not to seek to build nuclear weapons.

Trump said the 2015 accord did not do enough to curb the threat from Iran. He pulled out of the accord in May and began reimposing sanctions this month.

In the first day of hearings at the ICJ on Monday, Iran's lawyers said the sanctions were threatening the welfare of its citizens and disrupting tens of billions of dollars' worth of business deals.