Iran says the 2015 nuclear deal is not up for renegotiation, after US President Donald Trump threatened to withdraw from the agreement if its "terrible flaws" were not fixed. The next sanctions waivers are due in May.
Iran said on Saturday it would retaliate against the new sanctions, although it did not specify how.
One of the criticisms levelled at the nuclear deal is that it does nothing to address Iran's continuing ballistic missile program and involvement in conflicts such as Yemen and Syria.
Iran's Foreign Minister Mohammad Javad Zarif had earlier said on Twitter that the deal was "not renegotiable" and that Trump's move "amounts to desperate attempts to undermine a solid multilateral agreement".
The United States has failed to undermine the nuclear deal between Tehran and world powers, Iranian President Hassan Rouhani said in a statement broadcast on state television. "This is a last chance".
"Iran strongly announces that it will make no measure beyond its JCPOA commitments and will make no changes in the nuclear deal neither now nor in the future", the statement read.More news: 'AMERICA FIRST!': Trump Launches Latest Attack on DACA, Democrats
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So far, Trump has continued to follow Obama's lead in regularly signing sanctions waivers so that U.S. economic measures against Tehran do not "snap back".
The president's proposals to "fix the deal's disastrous flaws" include Iran's agreement to open all sites immediately to worldwide inspectors and an assurance from Tehran that it will never develop a nuclear weapon. Widespread protests in Iran over the last few weeks have focused on the country's faltering economy, however, as well as high unemployment and government corruption.
Washington policy hawks hailed Trump's decision, which they said would concentrate minds in Europe, where leaders have urged the United States president not to sabotage a deal they see as a landmark diplomatic success.
While there may be some relief that Trump has yet to torpedo the hard-won accord, there were clear signs of frustration from European capitals in the runup to the decision.
"So Trump now has issued explicit May deadline to Congress and Europeans: Fix Iran nuke deal or no more sanctions waivers", wrote Mark Dubowitz, head of the Foundation for Defence of Democracies.
Germany said it would continue to call for the deal's full implementation and would consult on a "common way forward" with the United Kingdom and France.
French President Emmanuel Macron called Trump on Thursday and stressed France's determination to see "the strict application of the deal and the importance of all the signatories to respect it".