By John Irish

KANANASKIS, Alberta (Reuters) -European foreign ministers told their Iranian counterpart in a call on Monday to return to nuclear negotiations with the U.S. and refrain from escalating conflict with Israel, to which Iran's foreign minister said Tehran's priority was to confront Israel for now, according to a French diplomatic source.

Israel launched what it called Operation Rising Lion against Iran's nuclear facilities in the early hours of Friday, just two days before U.S. and Iranian negotiators were due to resume talks to forge a new deal on Iran's nuclear programme.

Israel called it a preemptive strike designed to prevent Iran from developing nuclear weapons. Iran has denied plans to develop such weapons and retaliated by launching counterstrikes on Israel.

France, Britain and Germany, known as the E3, are party to the 2015 nuclear accord with Iran, which aimed to curb Iran's nuclear programme in return for sanctions lifting.

Last week they put forward a resolution that was approved by the board of governors of the International Atomic Energy Agency, a U.N. watchdog, which declared Iran in breach of its nuclear non-proliferation obligations.

"The ministers urged Iran to return to the negotiating table as quickly as possible, without preconditions," the source said, calling on Iran to avoid any headlong rush against Western interests. 

Iran's Foreign Minister Abbas Araqchi was quoted by state media saying that he had recalled Iran's seriousness in diplomacy and emphasised that, "Iran has never left the negotiating table, but that (Tehran's) focus at this stage is, of course, to effectively... confront aggression."

France's Foreign Minister Jean-Noel Barrot spoke to U.S. Secretary of State Marco Rubio ahead of the E3's call with Araqchi, the diplomatic source said. The source said the E3 had separately passed messages to Israel urging it to not strike Iranian authorities, infrastructure or civilian populations. 

The European powers, who were not part of Iran's nuclear negotiations with the United States, had grown increasingly frustrated by the U.S. strategy in the talks. An initial written proposal from the Trump administration at the end of May was deemed very tough and offered little in return for Iran.

As part of last week's IAEA resolution, European officials had said they could refer Iran to the United Nations Security Council later in the summer to add pressure on Iran if there was no progress in the nuclear talks.

That would be separate to them reimposing UN sanctions, known as the snapback mechanism, before October 18 when the 2015 accord expires.

The Europeans are the only ones who can launch the snapback mechanism, with diplomats saying the three countries had looked to set a final deadline of end of August to launch it. 

It was unclear what their policy would now be. French President Emmanuel Macron said on Sunday that given Europe's knowledge of the nuclear dossier, it should be a key protagonist if nuclear talks resume.

Asked about the call, which also included the EU's foreign policy chief, a source familiar with U.S. thinking said Washington was not overly concerned since the U.S. clearly had the biggest role to play in de-escalating the Israel-Iran conflict. 

"At the end of the day, there's only going to be one country in the driver's seat of ending the war, and that's going to be the United States, obviously in partnership with Israel," the source said.

"If the world jumps in and it becomes more of a collaborative effort, as long as it's not undermining the foreign policy strategy of the United States or its ally Israel, I'm sure there will be no concerns," the source said.

(Additional reporting by Andrea ShalalEditing by Tomasz Janowski and Nia Williams)