Speaking to the BBC, Mr Guterres said there was a real risk of war if the 2015 agreement was not preserved.
The US president has until 12 May to decide whether to stick with the deal.
Calling the Iran agreement an "important diplomatic victory" Guterres argued that, unless there is a good alternative, the deal should be maintained.
According to him, if one day there is a better agreement to replace it, it is fine, but we should not scrap it unless we have a good alternative.
However, if USA sanctions relief were to be lifted and thus the nuclear deal abandoned, this would trigger a backlash by Iran which could resume its nuclear arms program or "punish" United States allies in Syria, Iraq, Yemen and Lebanon, diplomats said.
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The rules were set six years ago when California and the Obama administration agreed to a single nationwide fuel economy standard. The states argue the EPA did not give evidence to support its decision to weaken the rule and they are now asking the U.S.
"The nuclear deal is based on lies".
Trump, meanwhile, has been a vocal critic of the deal, which was negotiated by the Obama administration and foreign ministers from Iran, Russia, China, U.K., France and Germany.
Iran's envoy to Britain has warned that if Washington pulls out of the agreement, known as the Joint Comprehensive Plan of Action (JCPOA), Tehran would no longer feel committed to implementing its provisions, Press TV reported.
Yet, Netanyahu stressed in his presentation that the Iranians "archived" their suspended nuclear program, so as to have it available for quick resumption.
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The project, he said, had the explicit goal of producing five warheads, each with the yield of 10 kilotonnes of TNT.
He said the United States had "consistently violated the nuclear deal, particularly by bullying others to preventing businesses to return to Iran".
European leaders, including French President Emmanuel Macron, have been pressing Trump to strengthen rather than abandon the three-year-old deal that took more than a decade to reach.
"I don't want to trivialize for a minute Israeli security concerns about Iran's conventional or unconventional weapons, or their commitment or intention to develop a nuclear weapons program", Aaron David Miller, a former State Department analyst and Mideast peace negotiator, told NPR on Tuesday. "Leaving the JCPOA will harm the peace and security of the Middle East region", he further said. It would also deliver a blow to Iranian President Hassan Rouhani, who's battling conservative hardliners at home.
He revealed that Israeli spies had managed to steal thousands of physical and electronic documents about the Iranian nuclear weapons program as it existed 15 years ago - an impressive piece of spycraft but old news.
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To Gerrard's credit, there was no b*****it in his reply, he admitted talks had taken place, adding that they had been "positive". Gerrard also made 114 appearances for England and captained the side at three of the six major tournaments he played at.