Iran says the United States is the "biggest violator" of international accords, a fact that President Donald Trump best demonstrated by abandoning the 2015 nuclear deal in breach of a United Nations Security Council resolution.

Bahram Qassemi, Iran Foreign Ministry spokesman, said Wednesday that Trump's decision in May was a violation of the UNSC Resolution 2231, which endorsed the nuclear deal between Iran and the P5+1 group of countries -- the US, the UK, France, China, Russia and Germany.

"The US is the biggest violator of international agreements and defying Resolution 2231 was the telltale sign of a unstable, unruly and unbiddable government," he told a press call.

Resolution 2231 enshrined the Iran nuclear agreement, officially known as the Joint Comprehensive Plan of Action (JCPOA), from which Washington has withdrawn under the pretext, among others, that it should have included Iran's missile program as well.

Under the deal, Tehran agreed to put limits on its nuclear program in exchange for the removal of nuclear-related sanctions.

Trump pulled out of the deal, vowing to resume all the sanctions and tighten the economic and political pressure until Tehran agrees to halt its development of ballistic missiles while also rolling back its regional influence.

Qassemi's words came in response to Christopher Ashley Ford, US Assistant Secretary of State for International Security and Non-Proliferation, who suggested Tuesday that the US could sit down with Iran to renegotiate the deal.

During his remarks at a conference in the UK, Ford accused Iran of violating the Nuclear Nonproliferation Treaty (NPT) and said Tehran had a tendency " to violate its obligations under multiple, legally-binding Security Council resolutions."

"Iran’s track record demonstrates, in painful detail, how little the world can trust Iran’s promises if its underlying capabilities are not subject to constraint," the US official added.

Qassemi dismissed Ford's remarks as "wishful thinking" and advised the American official to review his remarks once again to see how "unsubstantiated and flawed" they were.

He said despite the International Atomic Energy Agency's repeated confirmations that Iran was in compliance of the JCPOA , "the delinquent and lawbreaking US, illegally and unilaterally, left the deal without offering any reasons or evidence [of a breach.]"

He noted that Washington's disregard for international norms and double standard policies, which are evident after its withdrawal from the JCPOA, invalidate Ford and other American officials' statements with regard to the nuclear deal and Iran's missile program; hence the idea of renegotiating the agreement is "pointless."

Qassemi said Washington continues its hostile approach towards Iran and actively tries to persuade other signatories of the JCPOA by threatening to "punish" them.

Trump has made it clear that he would go after European companies that attempt to bypass US sanctions.

Iran and the European Union (EU), however, have been working on a mechanism that makes safe trade possible between the two sides.