"These sanctions like other unilateral US sanctions run counter to the main principles and rules of international relations and specifically, violate international undertakings under the UN Charter, the Algeria statement, Treaty of Amity and the ruling of the International Court of Justice, and the US should account for its violating acts on the international scene through judiciary channels," Foreign Ministry Spokesman Seyed Abbas Mousavi said on Thursday.
He added that the "US regime" bears the responsibility to compensate for the losses resulting from metal sanctions against Iran.
US President Donald Trump on Wednesday imposed new sanctions on Iran, targeting revenue from its exports of industrial metals.
An executive order issued by Trump covers Iran's iron, steel, aluminum and copper sectors, a White House statement said.
The decision was made on the same day that Iran's Supreme National Security Council (SNSC) announced in a statement on Wednesday that the country had modified two of its undertakings under the Joint Comprehensive Plan of Action in return for the US abrogation of the deal and other signatories inability to make up for the losses under the agreement, warning that modifications would continue if the world powers failed to take action in line with their promises.
"The Islamic Republic of Iran declares that at the current stage, it does not any more see itself committed to respecting the limitations on keeping enriched uranium and heavy water reserves," the statement said.
The statement gave the Group 4+1 (China, Russia, Britain and France plus Germany) "60 days to put into action their nuclear deal undertakings, specially in the banking and oil sectors, warning that "in case these countries fail to meet Iran's demands, the Islamic Republic of Iran will cease implementation of restrictions on uranium enrichment levels and measures related to the modernization of Arak Heavy Water Reactor as well".
"Once our demands are met, we will resume implementation of the ceased undertakings. Otherwise, the Islamic Republic of Iran will stop compliance with its other undertakings in consequent phases," the SNSC warned.
It underlined Iran's readiness to continue its consultations with the countries which have remained in the nuclear deal at all levels "but will show a firm and rapid reaction to any irresponsible measure, including referring the issue to the UN Security Council or imposition of more sanctions".
"The Islamic Republic of Iran's president has in his letter to the leaders of the nuclear deal member states clearly reminded them of the Islamic Republic of Iran's type of reaction," the statement added.
It reminded the G4+1 of Iran's good will during the nuclear talks, implementation of the nuclear deal and giving sufficient time to the other signatories to implement the deal, saying that it is now their turn to prove their good will and adopt serious and practical measures to protect the nuclear deal.
"The door of diplomacy will not remain open for a long time and the US and other members remaining under the nuclear deal are fully responsible for failure of the nuclear deal and any possible consequences," the statement said.
It underlined that the decision was made in line with defending the Iranian nation's security and national interests and materialization of Iran's rights stated in the paragraphs 26 and 36 of the nuclear deal.
Iranian President Hassan Rouhani in a letter on Wednesday also informed the Group 4+1 on stopping implementation of a number of Tehran's undertakings stated in the 2015 nuclear deal.
Iranian Deputy Foreign Minister for Political Affairs Seyed Abbas Araqchi submitted the letter to the ambassadors of the G4+1 to Tehran after they were called to the foreign ministry on Wednesday morning.
The letter contains decisions by the SNSC to "halt implementation of a number of the Islamic Republic of Iran's undertakings under the nuclear deal".
Also, another letter was sent by Iranian Foreign Minister Mohammad Javad Zarif to EU Foreign Policy Chief Federica Mogherini on Wednesday morning to inform her of details of Iran's measures.
Washington withdrew from the internationally-endorsed 2015 nuclear deal with Iran, reimposed the toughest-ever sanctions against the country and started a plan to zero down Tehran's oil sales.
Under the nuclear agreement reached between Iran and six world powers in July 2015, Tehran undertook to put limits on its nuclear program in exchange for the removal of nuclear-related sanctions.
Yet, Iran continued compliance with deal, stressing that the remaining signatories to the agreement had to work to offset the negative impacts of the US pullout for Iran if they want Tehran to remain in compliance.
Iranian officials had earlier warned that the European Union’s failure in providing the needed ground for Tehran to enjoy the economic benefits of the nuclear deal would exhaust the country's patience.
The US state department announced on Friday that it had not extended two waivers, one that allowed Iran to store excess heavy water produced in the uranium enrichment process in Oman, and one that allowed Iran to swap enriched uranium for raw yellowcake with Russia.
Until now, Iran was allowed to ship low-enriched uranium produced at Natanz to Russia before it hit the 300-kg limit and the US measure leaves no way for Tehran other than exceeding the ceiling for storing the enriched uranium in violation of the 2015 nuclear deal.
Also, the United States would no longer waive sanctions that allowed Iran to ship heavy water produced at its Arak facility beyond a 300-ton limit set in the 2015 nuclear deal to Oman for storage which again forces Tehran to store it inside country in violation of the nuclear deal.
In return, Iranian Parliament Speaker Ali Larijani said on Saturday said that Iran would continue uranium enrichment after Washington defied to extend waivers on swapping enriched uranium for raw yellowcake with Russia, a mechanism stated in the nuclear deal to ensure a ceiling of a 300kg enriched uranium stockpile in Iran.
"The Americans have stated in the past few days that Iran is not entitled to produce heavy water, while we have not violated the (2015) nuclear deal and the laws and if you (the Americans) do not buy it, it is not important and we continue what we are doing," Larijani said in Tehran, addressing a group of Iranian school teachers on the occasion of Teachers Day in Iran.
Reminding that Iran had been importing yellowcake to process it into enriched uranium and sold the final product to Russia to keep its enriched uranium stockpile under 300kg, as enshrined in the Joint Comprehensive Plan of Action, he noted the US' recent decision to end waivers on this JCPOA undertaking, and said the Americans had also voiced opposition to Iran's enrichment of uranium.
Larijani addressed the US and other western states, saying that Iran did not care if its enriched uranium was purchased or not as "Iran will continue enrichment", implying that Tehran would be forced to go above the ceiling if the stated JCPOA-related mechanism fails.
Larijani's remarks meant that Iran would not go for the second option which entails stopping heavy water or uranium production to avoid exceeding the stated ceilings if Oman and Russia choose to comply with the US sanctions in violation of the JCPOA.