The United States on Sunday said it was disappointed that Iran had ruled out an informal meeting to discuss ways to revive its 2015 nuclear deal with major powers, but said it remained ready to reengage in meaningful diplomacy on the issue.

"While we are disappointed at Iran’s response, we remain ready to reengage in meaningful diplomacy to achieve a mutual return to compliance with JCPOA commitments," a White House spokeswoman said, referring to the Joint Comprehensive Plan of Action, or Iran nuclear deal.

She said Washington would be consulting with its P5+1 partners, the four other permanent members of the United Nations Security Council — China, France, Russia, United Kingdom - plus Germany on the best way forward.