The root cause behind the escalating Iran nuclear crisis lies in the maximum pressure exerted by the U.S. on Iran, Chinese foreign ministry said Monday. 

Spokesperson Geng Shuang said China always believes that the full and effective implementation of the Joint Comprehensive Plan of Action (JCPOA) in accordance with the requirements of the UN Security Council resolutions is the only realistic and effective way to solve the Iran nuclear issue and ease tensions.  

Geng called on all parties to keep calm and restraint and solve problems through dialogue under the Iran nuclear deal joint commission. At the same time, the parties should also assume their own responsibilities and ensure the balance of rights and obligations of the nuclear deal, he said.

The U.S. "maximum pressure" against Iran is the root cause of the crisis concerning the Iran nuclear issue, stressed Geng. He hopes the U.S. will abandon its wrongful practices, respect the legitimate rights and interests of other parties, not hinder the implementation of the Iran deal and jointly commit to the political and diplomatic settlement of the Iran nuclear issue. 

In a joint statement issued Sunday, France, Britain and Germany reiterated their support for the JCPOA but said they were deeply troubled by recent events in the Gulf and concerned over U.S.-Iran relations. 

"We believe the time has come to act responsibly and seek a path to stop the escalation of tensions and resume dialogue," the statement read. 

The 2015 deal was reached between Iran and six world powers – Britain, China, France, Germany, Russia, and the U.S. – with Tehran agreeing to drastically scale down its nuclear program in exchange for sanctions relief.