If any anti-Iran decision is enforced by the US to the detriment of last year's nuclear deal, it will face a proportional response from the Islamic Republic, a top Iranian security official warned.
Secretary of the Supreme National Security Council Ali Shamkhani reiterated this position on the sidelines of a security conference in Tehran on Sunday.
"The Islamic Republic of Iran … will provide proportionate response to the US decisions that become effective," he was quoted as saying by IRNA.
The deal, known as the Joint Comprehensive Plan of Action, was reached by Iran, the United States and five other powers in July 2015 and took effect six months later to scale down Tehran's nuclear program in exchange for relief from international sanctions.
US Congressional Republicans have made repeated attempts to counter the accord, the latest being a measure to extend the Iran Sanctions Act for another decade.
US President Barack Obama is expected to sign the bill into law.
ISA has been in force since 1996 and will expire in about two weeks unless it gains presidential approval.
Leader of Islamic Revolution Ayatollah Seyyed Ali Khamenei and other top Iranian officials have railed against the Congress' move as a breach of the historic pact and have threatened to retaliate.
President Hassan Rouhani and his nuclear negotiating team have come under heightened criticism from rival conservatives who insist the deal has conceded too much to the western side.
Shamkhani is a member of a committee chaired by President Hassan Rouhani and tasked with monitoring the commitments of the other side to the agreement.
The panel convened last week to decide how to respond to the US Congress' legislation.
Details of the decisions made in the meeting were not released.
Asked to explain what action the panel decided for the government to take, the official said, "This is not a concern of just the government, but rather a concern of the [whole] system," without elaborating on the matter.
On the hostile remarks of hawkish US president-elect, Donald Trump, against Iran and the nuclear accord during his election campaign, Shamkhani said it is premature to know what policy Trump will adopt on Iran after taking office next month because he has not appointed all his Cabinet ministers.
"It is too soon to form a judgment based on Trump's team. The team is not complete yet," he said.
On the campaign trail, Trump sharply criticized the pact, describing it as "a disaster" and "the worst deal ever negotiated".
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