Talks between Israel and the Palestinians collapsed in April despite the efforts of US Secretary of State John Kerry to broker a deal, setting the stage for a bloody war in Gaza just a few months later.
On Sunday, Kerry met his Russian counterpart Sergei Lavrov, European Union foreign affairs head Federica Mogherini and UN Deputy Secretary General Jan Eliasson on the sidelines of the Munich Security Conference to review the situation in the region.
"The Quartet underlined the importance of the parties resuming negotiations as soon as possible with a view to reaching a just, lasting and comprehensive peace," a statement said.
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The Quartet also "recalled the importance of the Arab Peace Initiative -- with its vision for a comprehensive settlement of the Arab-Israeli conflict -- and the vital role of Arab partners," it said.
"Pending the resumption of negotiations, the Quartet called on both parties to refrain from actions that undermine trust or prejudge final status issues."
The Quartet was set up in Madrid in 2002 as part of efforts to find a comprehensive settlement to the conflict, with the Arab Peace Initiative approved by the Arab League the same year.
The four parties on Sunday also expressed deep concern "over the difficult situation in Gaza" where reconstruction needed to be accelerated to repair the massive destruction of last year's war.