"I call on other JCPOA participants to abide fully by their respective commitments under the JCPOA and on all other member-states to support this agreement," Guterres said in a statement, referring to the Joint Comprehensive Plan of Action (JCPOA), the formal name of the nuclear deal.
The deal reached between Iran and six world powers – Britain, China, France, Germany, Russia and the United States - imposed curbs to Iran's nuclear program in exchange for sanctions relief.
Trump said Tuesday the agreement was "defective" as he announced the US withdrawal and a decision to re-impose sanctions.
Guterres said he was "deeply concerned" by the US decision to pull out of the agreement that he again described as a "major achievement in nuclear non-proliferation and diplomacy".
The agreement has "contributed to regional and international peace and security," he said.
France, Britain and Germany said they remained committed to the deal and vowed to work on a broader accord with Iran.
The agreement was endorsed in a resolution adopted by the Security Council.