German Chancellor Olaf Scholz on Monday said there was no reason for Iran not to sign the nuclear deal and that European countries would remain "patient".
But Mr Scholz admitted he did not expect an agreement in the immediate future.
He spoke after meeting Israeli Prime Minister Yair Lapid in Berlin. Mr Lapid insisted that restoring the 2015 agreement would be “a critical mistake".
Germany, along with France, Britain, Russia and China, is still a party to the deal and involved in talks on its revival that have dragged on for more than a year.
The European countries “have made proposals and there is no reason now for Iran not to agree to these proposals", Mr Scholz said.
"But we have to take note of the fact that this isn’t the case, so it certainly won’t happen soon, although it looked for a while like it would.
“We remain patient but we also remain clear: Iran must be prevented from being able to deploy nuclear weapons.”
He said that “a functioning international agreement to limit and monitor the Iranian nuclear programme is the right way” to do that.
But Mr Lapid said “it is time to move past the failed negotiations with Iran", which he said could not and would not achieve the goal of stopping Iran obtaining a nuclear weapon.
His office said he also shared intelligence with the German government.
“Removing sanctions and pouring hundreds of billions of dollars into Iran will bring waves of terrorism, not only to the Middle East, but also across Europe,” Mr Lapid said.
Iran's nuclear programme - in pictures
Israel, which encouraged the US to withdraw from the nuclear deal in 2018, has opposed a renewed agreement between Iran and the world powers.
It says lifting sanctions will allow Iran to funnel billions of dollars to hostile militant groups and says an improved deal must also address Iran’s regional military activities and support for hostile groups such as Hezbollah in Lebanon and other militias in Syria.
Israeli Defence Minister Benny Gantz on Monday said Iran had built at least 10 plants “for mid- and long-range, precise missiles and weapons” in neighbouring Syria, including one reportedly hit by Israel in a recent air strike.
Mr Gantz told the Jerusalem Post Conference in New York that Iran has produced “more and more advanced centrifuges, including at underground facilities where activities are prohibited”, and called for Tehran to be held accountable.
His remarks could not be independently verified.
The US pulled out of the nuclear accord under then President Donald Trump and reimposed sanctions on Iran, prompting Tehran to start backing away from the deal’s terms.
Iran this month responded to a final draft of a roadmap for parties to return to the tattered nuclear deal and bring the US back on board.
An investigation by the International Atomic Energy Agency into man-made uranium particles found at three undeclared sites in the country has become a key sticking point in the talks for renewing the agreement.
Iranian President, Ebrahim Raisi, has said that the IAEA investigation into the issue must be halted for the 2015 deal to be renewed.
The IAEA, the UN nuclear watchdog agency, has for years sought answers from Iran to its questions about the particles.
US and Israel pledge to deny Iran nuclear weapons - video
US and Israel pledge to deny Iran nuclear weapons
US intelligence agencies, western nations and the IAEA have said Iran ran an organised nuclear weapons programme until 2003. Iran long has denied ever seeking nuclear weapons.
Germany, France and Britain said in a statement at the weekend that “Iran must fully, and without delay, cooperate in good faith with the IAEA".
IAEA Director General Rafael Grossi said at the agency’s Vienna headquarters that he hoped Iran would start co-operating “as soon as possible".
“We are ready; we want this to happen,” Mr Grossi said.
“We are not in the business of aggravating or creating situations. We just want this issue to be clarified, so I really hope that they will start looking into this issue in a different way.”
