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."
As IAEA reports show Iran's nuclear efforts advancing, the US and its allies have few viable options to respond.
Now is the time to crack down on nuclear violations, precisely now that Iran has shown all of its cards.
Asked in a radio interview about a hypothetical nuclear option, Heritage Minister Amichai Eliyahu had replied: "That's one way."
President of the Atomic Energy Organization of Iran also critiqued Western countries in meeting with Director General of the IAEA in Vienna.
Russia made the remarks after Israel's atmoic energy chief spoke at the IAEA conference in Vienna.
“Iran is still the spearhead of regional instability, and is a threat to peace and security worldwide,” Israel Atomic Energy Commission head Moshe Edri said at the IAEA conference.