President Hassan Rouhani has called for unity among Iran's political factions to overcome conditions which he said may be harder than those during the 1980s war with Iraq.
The announcement came exactly a year after the United States withdrew from the deal, known as the Joint Comprehensive Plan of Action (JCPOA), with further measures threatened if the agreement's other signatories fail to mitigate the impact of renewed American sanctions within 60 days.
The Iranian president said that while "the pressures by enemies is a war unprecedented in the history of our Islamic revolution ..."
Iran announced earlier this month that it will stop respecting some limits on its nuclear activities imposed under the landmark 2015 deal.
Under the accord, Iran had agreed to limit its sensitive nuclear activities and allow in worldwide inspectors in return for sanctions relief.
The sanctions prevent U.S. companies from trading with Iran directly and also with any foreign firms or countries that are dealing with Iran.
The Europeans said they would monitor the findings of regular International Atomic Energy Agency reviews of whether Iran was honoring its obligations under both the nuclear agreement and the Treaty on the Non-Proliferation of Nuclear Weapons.
However, that projection preceded another move by the United States to tighten sanctions: the end to exemptions enjoyed by China, India, Japan, South Korea and Turkey, all five of which have been buying Iranian oil.
Yadollah Javani, deputy commander of Iran's Revolutionary Guard Corps (IRGC) added Iran does not intend to talk to the US.
These included, MARAD said, oil production infrastructure, after Tehran threatened to close the vital Strait of Hormuz chokepoint through which about a fifth of oil consumed globally passes.
What is the USA doing? Washington also approved a new deployment of Patriot missiles to the Middle East, a USA official said on Friday. And on Friday, the Pentagon announced it would be returning a Patriot missile battery to the wider Mideast, as well as sending the USS Arlington, an amphibious warship carrying marines, to join the Lincoln.
The U.S. Air Force has confirmed that B-52 bombers sent by the White House to the Persian Gulf to counter unspecified threats from Iran have arrived at a major U.S. air base in Qatar.
The US says the deployments of military hardware to the region comes in response to "heightened Iranian readiness to conduct offensive operations". Iran dismissed the claim as nonsense.
"These are all allegations which are being produced by the same people who, in the run-up to the USA invasion of Iraq, did the same", Ravanchi said, in an apparent reference to national security adviser John Bolton, who worked in George W. Bush's administration during the US-led invasion of Iraq.
On Wednesday, Zarif said limiting Iran's level of commitment to the nuclear deal does not mean that the deal is dead, but warned Europe that they have a "narrowing window" of diplomacy to save the deal.