The summit in the Swiss resort also comes after Iran earlier this month shot down a Ukrainian passenger plane, killing all 176 people on board.
Iran has accused the three EU member states of inaction over sanctions the United States reimposed on it after unilaterally withdrawing from the landmark accord in 2018.
Since May 2019, Iran has progressively scaled back some commitments under the agreement in response to the US sanctions and Europe's inability to circumvent them.
Washington has said it plans to place such weapons in the Asia-Pacific following the US withdrawal from the Intermediate-Range Nuclear Forces Treaty
Possession of the uranium doesn't put Iran much closer to developing a nuclear weapon, but it does raise troubling questions about the future of nuclear non-proliferation
Iran has repeatedly warned Europe in recent weeks that it would begin walking away from an accord neutered by a maximalist American campaign of sanctions
China's foreign ministry ruled out negotiating a new multilateral pact to replace the Intermediate-Range Nuclear Forces Treaty