"We are deeply disappointed by US steps to re-impose its national sanctions against Iran," the Russian Foreign Ministry said in a statement on Tuesday.
The ministry said it will do "everything necessary" to save the historic nuclear deal, officially known as the Joint Comprehensive Plan of Action (JCPOA), and to protect its shared economic interests with Iran.
"This is a clear example of Washington violating UN Resolution 2231 and international law," it added.
The JCPOA between Iran and the five permanent members of the UN Security Council plus Germany was endorsed in the form of the UN Security Council Resolution 2231, Presstv reported.
In defiance of warnings from the European Union, the JCPOA signatories and many international players, President Trump signed an executive order re-imposing a first round of sanctions on Iran, which were lifted under the nuclear deal, to levy "maximum economic pressure" on the Islamic Republic.
“[The Iran nuclear deal] a horrible, one-sided deal, failed to achieve the fundamental objective of blocking all paths to an Iranian nuclear bomb,” Trump said in a statement on Monday.
The sanctions will cover Iran’s purchases of dollars, its trade in gold and precious metals, and its automotive sector. Further sanctions on oil and transactions with the central bank of Iran will come into effect on November 4.
The Russian Foreign Ministry further said the multi-party nuclear agreement has "shown its effectiveness."
It added that the international community should not "allow such significant achievements in multilateral diplomacy to be sacrificed in the name of American aspirations to settle political scores with Iran."
"As long-term experience has shown, it will not be possible to gain concessions from Iran using pressure," the statement pointed out.
The European Union on Monday voiced its deep regret over the US renewal of sanctions on Iran, saying the 28-nation bloc and other signatories would work on keeping financial channels with Iran open.
"The JCPOA is working and delivering on its goal, namely to ensure that the Iranian program remains exclusively peaceful, as confirmed by the International Atomic Energy Agency (IAEA) in 11 consecutive reports," the bloc said in a statement.
Syria: US renewal of sanctions on Iran 'illegal'
Syria also on Tuesday slammed the United States' re-imposition of sanctions on Iran, saying it was an "illegal" move driven by the "arrogance."
Syria "sharply condemned the American administration's decision to re-impose economic sanctions on Iran," the official Syrian Arab News Agency (SANA) quoted a Foreign Ministry official as saying.
"These unilateral actions are illegal under international law and confirm that the US administration's policies have a proclivity for hegemony and arrogance," the Syrian official added.
The official expressed Syria's full solidarity with Iran "in facing the hostile policies of the US administration" and added, "Iran's leadership, government, and people will triumph over all the ramifications of these steps."
UN opposes US sanctions against Iran, supports JCPOA
The United Nations said on Monday it will continue to encourage support for all governments for the Iran nuclear agreement despite the US re-imposition of sanctions on Tehran.
UN Secretary General Antonio Guterres continues to view the nuclear deal as a diplomatic achievement, Farhan Haq, a UN spokesperson said.
In response to the possible humanitarian impacts of the sanctions, Haq said, “We will have to see what effects of these measures are.”
He emphasized that it is important that “Iran and the other parties comply with the terms of the JCPOA “regardless of the steps that are being taken.”
The UN spokesperson said the nuclear accord is the best way of resolving this particular situation and this is the reason that “we would encourage all countries to do what they can to support the agreement.”
In a live televised interview on Monday, Iranian President Hassan Rouhani said the US administration is no more able to prove its trustworthiness for any negotiations after its withdrawal from the Iran nuclear deal in May and a number of other international treaties.
"We are always in favor of diplomacy and talks ... But talks need honesty ... The US re-imposes sanctions on Iran and pulls out of the nuclear deal, and then wants to hold talks with us," the Iranian president said.
The European Union said on Tuesday the international community has an obligation to maintain economic relations with Iran, despite the United States’ unilateral withdrawal from the multilateral deal with the Islamic Republic that could hamper such relations.
Iraq refuses to support US sanctions on Iran: PM
Iraqi Prime Minister Haider al-Abadi also said his country does not agree with US sanctions against Iran.
"As a matter of principle we are against sanctions in the region. Blockade and sanctions destroy societies and do not weaken regimes," he said at a news conference on Tuesday.
"We consider them (sanctions on Iran) a strategic mistake and incorrect but we will abide by them to protect the interests of our people. We will not interact with them or support them but we will abide by them," he added.