The European powers rejected that ultimatum.
The meetings in Brussels followed an announcement by Tehran last week that it will scale back some of its commitments under the agreement if world powers do not protect its interests against us sanctions.
Over the recent weeks, Washington has ratcheted up pressure against Tehran with a series of sanctions, designations and military threats.
What is the Iran nuclear deal? "He's always welcome obviously, but there are no precise plans at the moment", she said.
"We will be here all day with a busy agenda".
Jeremy Hunt, Britain's foreign minister, warned that armed conflict might be sparked "by accident" as tensions mount.
"We agree on much more than we disagree". The European parties insist the agreement was never meant to address those issues but has been effective in curbing Iran's nuclear ambitions.More news: Eden Hazard drops major hint regarding his Chelsea future
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United States Secretary of State Mike Pompeo is also expected to meet European Union officials in Brussels on Monday to talk about Iran. They said, 'Oh, we're not tough on Russian Federation.' I only wish they would have stopped the election interference. We believe that Iran should try talks instead of threats.
"We would expect coordinated steps and coordinated thinking in this regard", Lithuanian Foreign Minister Linas Linkevicius told reporters in Brussels.
Iran says at any given time that its demands are met, it will resume complying with the suspended commitments, which have been made impossible to continue due to the U.S. measures and sanctions, according to FM Zarif.
US President Donald Trump on Monday warned Iran would "suffer greatly" if it does "anything".
But the Europeans said they are fearful about the behaviour of both Iran and the Trump Administration. But they told ABC News the trip is a "good opportunity... to take that conversation [with Russia] to a higher level and for a frank exchange of views on where the challenges and opportunities are". "If they do anything they will suffer greatly".
The UAE said on Sunday that four commercial vessels were sabotaged near Fujairah emirate, one of the world's largest bunkering hubs lying just outside the Strait of Hormuz.
"I think this is Moscow testing whether there is a new modus operandi in Washington, (after) the release of the Mueller report", said Katz, now a senior fellow at The German Marshall Fund of the United States.
Iran's foreign ministry called the incidents "worrisome and dreadful" and asked for an investigation.