US Secretary of State Mike Pompeo says Washington is canceling a 1955 treaty with Tehran after the International Court of Justice (ICJ) ordered the United States to halt the unilateral sanctions it recently re-imposed on "humanitarian" supplies to Iran.

“I’m announcing that the United States is terminating the 1955 Treaty of Amity with Iran, this is a decision that is 39 years overdue,” Pompeo told reporters Wednesday at the State Department.

“In July, Iran brought a meritless case in the International Court of Justice alleging violations of the Treaty of Amity,” Pompeo said.

"We're disappointed that the court failed to recognize that it has no jurisdiction to issue any order relating to these sanctions measures with the United States, which is doing its work on Iran to protect its own essential security interests," he added.

"Iran has attempted to interfere with the sovereign rights of the United States to take lawful actions as necessary to protect our national security and Iran is abusing the ICJ for political and propaganda purposes," the top American diplomat said.

He claimed the United States would work to ensure it is providing humanitarian assistance to the Iranian people.

The Hague-based court, which is the principal judicial organ of the United Nations, announced its ruling on Wednesday regarding the July lawsuit brought by Tehran against Washington's decision to re-impose unilateral sanctions following the US exit from the 2015 nuclear deal.

The decisions of the ICJ – which rules on disputes between UN member states – are legally binding and cannot be appealed.

Iran’s lawsuit argued that the sanctions violate the terms of the 1955 Treaty of Amity between Iran and the US. It also called on the court to order Washington to immediately suspend the measures.

The treaty established economic relations and consular rights and was signed during the terms of former US President Dwight Eisenhower and former Iranian Prime Minister Hossein Ala.

In May, US President Donald Trump pulled his country out of the 2015 nuclear agreement, called the Joint Comprehensive Plan of Action (JCPOA), despite objections from the other signatories to the accord.

In August, he re-imposed the first round of sanctions on Iran. The second phase of US bans will come into effect next month.

In a post on his Twitter account on July 16, Iran’s Foreign Minister Mohammad Javad Zarif said the ICJ complaint challenged the US “unlawful re-imposition of unilateral sanctions.”