The report, which is confidential but was seen by multiple news agencies, also stated that Iran has "not pursued the construction" of its heavy-water reactor at Arak, which would give it the capability to produce weapons-grade plutonium.
The agency uses electronic seals and online enrichment monitors to get reports to inspectors in real time. It also conducts on-site visits and has access to satellite imagery.
Iran's envoy to the agency, Reza Najafi, hailed the report as reflective of the watchdog's "unbiased and professional" work, Iranian media reported. The State Department said in a statement that the United States has "full confidence in the agency and its highly skilled and professional inspectors."
The document published Thursday is the watchdog's eighth certification of Iran's compliance since the deal took effect in January 2016. It comes just a week after the U.S. envoy to the United Nations, Nikki Haley, visited the agency in Vienna to convey the administration's concerns about ensuring Iran's strict compliance with the agreement. The administration has placed the accord, which was negotiated by the Obama White House, under interagency review. It says the agreement does not do enough to address other issues, such as Iran's ballistic missile development or human rights violations in the region.
Haley called on the agency to "pursue every angle possible" to monitor Iran's activities, including inspections of military sites Iran says are not part of its nuclear research program. Under the accord — known as the Joint Comprehensive Plan of Action, or JCPOA — the agency can request access to military sites if it decides there is credible evidence of malfeasance.
A U.S. official said Thursday that Haley "did not ask the IAEA to inspect any specific sites, nor did she provide the IAEA with any new intelligence." The official spoke on the condition of anonymity because the agency's report has not officially been made public.
"She conveyed that the IAEA will need to continue to robustly exercise its authorities" to monitor the JCPOA, the official said, "including access to undeclared and military-affiliated sites where the agency has questions about nuclear-related activities."
In a statement Thursday, Haley did not directly address the report. Instead, she referred to a comment made earlier this week by a top adviser to Iran's supreme leader, Ayatollah Ali Khamenei, who dismissed the U.S. call for further inspections as a "dream" that would never be fulfilled.
"If inspections of Iranian military sites are 'merely a dream,' then Iranian compliance with the JCPOA is also a dream," she said in the statement.
Later, she tweeted a different version of the same quote, declaring that if Iran "rejects a valid request for inspections, then the nuclear deal as they say is 'merely a dream.' "
But critics see the push for further access as an attempt to politicize the IAEA's work, and potentially force Iran to withdraw from the deal. The administration, including President Trump, has repeatedly threatened to pull out of the accord. Trump told the Wall Street Journal in July that he "did not expect" to declare Iran compliant in the coming months, despite a lack of public evidence of any Iranian violations.
"Almost any other U.S. administration would have a very hard time shrugging off the data provided by the IAEA, since it's such a trusted source," said Colin Kahl, who was a deputy assistant to President Barack Obama. Kahl now serves on the advisory council of Diplomacy Works, an organization committed to upholding the JCPOA.
"However, President Trump has shown disdain for the Iran deal, and most multilateral efforts," he said. "So the IAEA report does make it harder for the Trump administration to make its case for decertifying Iran's compliance . . . but that doesn't necessarily make it less likely to happen."