This marks the IAEA's first condemnation of Iran since 2022. Iran announced that it would respond, but didn't mention how.
The US government is reportedly opposed to confronting Iran at this stage because of a mix of concern that Tehran might escalate the situation into a crisis.
In recent months, multiple top Iranian officials have threatened the West that it might publicly decide that nuclear weapons are not prohibited by Islam.
The deaths of Iran's president and foreign minister in a helicopter crash have caused a pause in the UN nuclear watchdog's talks with Tehran.
IAEA Director General Rafael Grossi said Iran closed its nuclear facilities on Sunday over "security considerations" and that while they reopened on Monday.
Media reports indicate that Iran’s proxies have stopped attacking US interests after the visit of the Revolutionary Guards Quds Force Brig.-Gen. Esmail Qaani to Baghdad.
Iran says its aims are entirely peaceful and it has the right to enrich to high levels for civil purposes.
Under a defunct 2015 agreement with world powers, Iran can enrich uranium only to 3.67%.
Iran denies seeking nuclear weapons but no other state has enriched to that level without producing them.
"The Iranians are accumulating [uranium]. They say it's for civilian purposes, but we haven't seen much of that in use. It is, in fact, being stored."