"We hear loud statements that not only call into question the legal validity of international treaties, but also declare the priority of self-serving unilateral approaches over decisions taken in the framework of the United Nations," Russian Foreign Minister Sergey Lavrov said in an address to the UN General Assembly, according to the text of his speech published by the UN media center.
Without mentioning US President Donald Trump by name, he criticized attacks launched against the basic principles of international agreements, including the Iran nuclear deal.
Trump, who has embraced nationalism, railed against a number of international agreements, leaving him at odds with world leaders and past US foreign policy.
Lavrov called the US unilateral exit from the nuclear agreement—formally known as the Joint Comprehensive Plan of Action—a violation of UN Security Council Resolution 2231, which underpinned the accord.
"This is despite the fact that Iran is fully complying with its obligations," he said, adding that Washington's decision has come on top of the lack of progress in the ratification of the Comprehensive Nuclear-Test-Ban Treaty and the establishment of a zone free of weapons of mass destruction in the Middle East.
"We will do everything possible to preserve the deal that was approved by the UNSC," Russia's chief diplomat said.
He lamented that diplomacy and the culture of negotiations and compromise have been increasingly replaced by dictates and unilateral extraterritorial restrictions put in effect without the consent of the Security Council.
"Such measures, applied already to dozens of countries, are not only illicit, but also ineffective," he added.
Trump abandoned the 2015 nuclear deal in May 2018 and reimposed sanctions that have an extraterritorial impact on the country, arguing that the agreement does not cover its ballistic missile program or its role in the Middle East.
However, at a news conference after his speech, the Russian foreign minister characterized US policy on Iran as misguided and defended it from charges of being a state sponsor of terrorism.
"We do not have proof that … Iran is a state that sponsors terrorism," Lavrov said, while defending his country's partnership with Iran to prop up Syrian President Bashar al-Assad's government in the ongoing civil war, despite US and Israeli demands that Iran withdraw from Syria.
And he suggested that western efforts to curb Iran's influence throughout the Middle East are unrealistic.
Chinese State Councilor and Foreign Minister Wang Yi also used his speech to the annual gathering of global leaders to express support for the Iran deal, the UN media center reported.
"Now is a crucial time for the continued implementation of the agreement. It serves the common interests of all the parties concerned and the international community at large," he said.
Wang stated that if the agreement is not implemented, the international nuclear non-proliferation regime would be undermined, the authority and role of the Security Council would be challenged and peace and stability in this region and the wider world would be jeopardized.
"No one stands to gain from this scenario," the Chinese diplomat said, urging the parties to the agreement to respect it.
Wang added that all concerns regarding the deal can be resolved through dialogue and consultation.
In addition, Germany's Federal Minister for Foreign Affairs Heiko Maas told the UN General Assembly that European powers will continue to back the agreement.
"We are working on keeping economic exchange with Iran possible, and we call on Iran to continue to fully implement its commitments," he added, saying that the survival of JCPOA will make it easier to find solutions to conflicts in countries such as Yemen and Syria.
Earlier, French President Emmanuel Macron and British Prime Minister Theresa May had expressed disagreement with Trump's assessment of the nuclear deal, reaffirming their determination to keep it alive.