International Atomic Energy Agency (IAEA) Director General Yukiya Amano made the remarks in Tehran, where he met with high-level officials including Iranian President Hassan Rouhani.
Amano echoed the statement on Monday in Abu Dhabi, where a U.N. conference on nuclear energy is taking place. He said, "The IAEA can state that such nuclear-related commitments are being implemented."
"I requested that Iran ... fully implement the nuclear-related commitments. This (was) the main thrust of the meeting in Iran ... Regarding the activities of our inspectors, they are discharging their responsibility without problem," Amano said.
Al Jazeera describes Amano's latest "verification of compliance" as "a moment of vindication for Iran and another international rebuke of the White House."
Rouhani, for his part, said Sunday, "We should not allow the (nuclear deal), as an important achievement, to be undermined, and we must consolidate this important international commitment with full cooperation."
Roughly two weeks ago, President Donald Trump decertified the deal, punting the issue to the Republican-controlled Congress and sparking warnings that the move was "a recipe for disaster."
As Reuters previously noted, "none of the other signatories to the deal—Britain, France, Germany, Russia, China, Iran, and the European Union—have cited serious concerns, leaving the United States isolated."
The administration's apparent position is also out of step with the American public's. A CNN poll this month revealed that two-thirds of Americans are opposed to the U.S. ditching the deal.