They also said the reasons cited by President Trump for reimposing the sanctions were unfounded because the International Atomic Energy Agency (IAEA) had repeatedly confirmed that Iran was complying with the terms of the nuclear deal.
"This policy is nothing but naked economic aggression against my country", he said. He said sanctions are already having damaging effects on Iran's economy and society and threaten to further destabilize the volatile Mideast.
Iranian officials have also vocalized the resistance to the US naval presence within the gulf.
And on Wednesday, United Nations Special Rapporteur Idriss Jazairy, a former Algerian ambassador who was appointed by the U.N. Human Rights Council, said the sanctions were illegitimate and contribute to the economic hardship of everyday Iranians.
Tehran filed its case before the ICJ in late July, calling on the tribunal to order the immediate lifting of sanctions pending a definitive ruling. A final decision could take years.
While Trump pulled the United States out of the 2015 nuclear pact, other signees of the treaty - mainly Washington's European allies - urged Washington to remain in the deal and have vowed to stay in it themselves.
Pompeo said lawyers would "vigorously defend" the USA and "and we will continue to work with our allies to counter the Iranian regime's destabilizing activities in the region, block their financing of terror, and address Iran's proliferation of ballistic missiles and other advanced weapons systems that threaten worldwide peace and stability". Iran's currency, the rial, has lost about half of its value since April.
White House wobbles on U.S. flag after McCain death
Trump's remarks-or lack thereof-came after the president and McCain sparred on a variety of topics over the last few years. McCain will be buried Sunday at the US Naval Academy in Annapolis, Maryland, in a private funeral service.
Worldwide companies including French oil firm Total and Germany's Siemens have suspended operations in Iran since Trump announced the USA withdrawal in May.
In a written statement, U.S. Secretary of State Mike Pompeo called the legal move an attempt by Tehran "to interfere with the sovereign rights of the United States to take lawful actions, including re-imposition of sanctions, which are necessary to protect our national security".
Hearings in that case are due to start on October 8. "This policy is plainly in violation of the 1955 Treaty of Amity". "The United States has claimed that the very objective of these measures is to cause maximum damage to Iran".
U.S. lawyers are expected to argue that the United Nations court should not have jurisdiction in the dispute, that the friendship treaty is no longer valid and that the sanctions Washington has levied against Tehran do not violate it.
Trump said the sanctions would turn up the financial pressure on Tehran to come to a "comprehensive and lasting solution" regarding its activities such as its "ballistic missile programme and its support for terrorism".
Despite the treaty, the two countries have not had diplomatic ties since 1980.
Experts expect them to challenge the ICJ's jurisdiction.
Iran routinely refers to the USA as "the enemy" and its officials chant "Death to America" at official functions.