Germany's Chancellor Olaf Scholz said on Monday that he "regrets" that Iran has not yet responded "positively" to nuclear deal talks.
This week, Germany, France and the UK raised “serious doubts” about Iran's sincerity in restoring the deal, known formally as the Joint Comprehensive Plan of Action (JCPOA).
Mr Scholz warned Tehran that any delay or hesitation would put any accord out of reach "in the near future".
"I regret that Iran has not yet given a positive response to proposals from the European co-ordinators," he said at a press conference in Berlin during a visit by Israeli Prime Minister Yair Lapid.
European partners have made proposals and say there is no reason for Iran to reject the new deal, the German official said.
"But we have to note that this is not the case, and will not happen certainly in the near future."
Germany is one of three European nations party to the agreement, along with France and Britain.
Mr Lapid called for collaboration against the growing threat of Iran becoming a nuclear state.
"It’s time to move past failed negotiations and that returning to the agreement under current conditions would be a mistake," Mr Lapid said.
"They cannot and will not achieve the goal we all share to stop Iran from getting a nuclear weapon," the Israeli official said.
The development comes as Iran said on Monday it is ready to continue co-operation with the UN nuclear watchdog while revealing a drone capable of hitting major cities in Israel. Israel has threatened to attack Iranian nuclear sites if diplomacy fails to revive the 2015 nuclear pact, which the Donald Trump administration unilaterally withdrew from in 2018.
Speaking after European powers expressed frustration with Tehran's apparent lack of commitment to salvage the agreement, Iranian Foreign Ministry spokesman Nasser Kanaani urged the International Atomic Energy Agency (IAEA) "not to yield to Israel's pressure" over Tehran's nuclear activities.
