Fears of a Middle East war with global repercussions have risen since U.S. President Donald Trump withdrew last year from the 2015 deal and revived a panoply of sanctions meant to push Tehran into wider security concessions.
Iran has retaliated by breaching the deal, resuming uranium enrichment seen in the West as a potential conduit to developing an atom bomb, but faces severe economic damage under intensified U.S. sanctions designed to strangle its vital oil trade.
"We have a hard battle ahead, but we shall surely win," Rouhani said on live state television.
"We are not acting on the assumption we will get results through talks and accords," Rouhani said, alluding to European powers trying to salvage the deal that reined in Iran's disputed nuclear advances but unable to protect from U.S. sanctions the trade benefits that Tehran was promised in return.
"Instead we are planning based on the assumption that we will not achieve results. Our budget for this year and next, our ministries are also acting on this basis ... We are acting and going step-by-step with long-term prudence."
The downbeat remarks by Rouhani, architect of the landmark 2015 accord and a strong proponent of negotiations, hinted he was losing hope of avoiding a final collapse of the deal, though he left the door open to further contacts with Europe.ATTACKS ON OIL TANKERSAfter several attacks in May and June on oil tankers - blamed by Washington on Tehran, which denied responsibility - U.S. President Donald Trump has been trying to forge a military coalition to secure Gulf waters, though European allies have been loath to join for fear of provoking open conflict.Britain, France and Germany have instead appealed for diplomatic moves to defuse the crisis. But longtime foes Tehran and Washington have taken hard lines and on Wednesday the Trump administration slapped sanctions on Iran's foreign minister in an effective rebuff to European calls for direct dialog."They (Americans) are resorting to childish behavior... They were claiming every day 'We want to talk, with no preconditions'...and then they sanction (our) foreign minister," Rouhani said earlier on state television.Foreign Minister Mohammad Javad Zarif, a pivotal player in the nuclear deal who was educated and lived for years in the United States, said the U.S. action would not affect him as he had no property or other interests in America.U.S. AFRAID OF ZARIF'S WORDS, IRAN SAYS"A country which believes it's powerful and a world superpower is afraid of our foreign minister's interviews," Rouhani said, referring to numerous interviews that Zarif - a fluent English speaker - gave to American media when he visited New York for a United Nations conference in July."If they're serious about negotiations, who other than (our) foreign minister can be their interlocutor?" Rouhani added.U.S. Treasury Secretary Steven Mnuchin said Zarif was being sanctioned because he "implements the reckless agenda of Iran's Supreme Leader...(We are) sending a clear message to the Iranian regime that its recent behavior is completely unacceptable."In repudiating the nuclear deal reached by his predecessor Barack Obama, Trump said he wanted to secure a more far-reaching accord that would not only put stricter limits on Iran's nuclear activity but also curb its ballistic missile program and end its support for armed proxies in Syria, Iraq, Yemen and Lebanon.Iran has long said its nuclear work is solely for civilian energy and its missiles only for defense and deterrence.
NO SWAP OF SEIZED TANKERS, BRITAIN SAYS
As U.S.-Iranian tensions have spiraled, the security of shipping in the Gulf, through which about a fifth of the world's oil passes, has shot up the international agenda.
Washington has accused Iran of being behind explosions that holed six oil tankers in May and June.
In July, Iran seized a British-flagged tanker in the Strait of Hormuz, the Gulf's outlet to the open seas, in apparent retaliation for Britain's seizure of an Iranian ship accused of violating European sanctions by taking oil to Syria.
Britain on Thursday ruled out a swap of the two tankers. "We are not going to barter: if people or nations have detained UK-flagged illegally then the rule of law and rule of international law must be upheld," Foreign Secretary Dominic Raab said.
In a sign of increasing jitters over security in the Gulf, Royal Dutch Shell said on Thursday it was not taking any British-flagged tankers through the Strait of Hormuz for the time being.
The U.S. Embassy in Berlin said on Tuesday the United States had asked Germany to join France and Britain in a mission to protect shipping through the strait and "combat Iranian aggression." Germany rejected the request.
On Thursday, Richard Grenell, U.S. ambassador to Germany, urged Berlin to take on a global responsibility to match its economic might. "Germany is the biggest economic power in Europe. This success brings global responsibilities," he said.