"We will be unswerving in upholding it," Chinese Foreign Minister Wang Yi said on Friday, ABC News reported.
Speaking alongside EU foreign policy chief Federica Mogherini, he said the agreement has been endorsed by the UN and that "every party has the duty to implement it."
Praising China, Mogherini said that the EU and other partners are working "in full coordination" to save the pact.
Last month Donald Trump unilaterally withdraw from JCPOA.
MAH/PR