The decision serves as pressure ahead of the inauguration of President-elect Joe Biden, who has said he is willing to re-enter the Iran nuclear deal.
Any work at the Fordo facility likely will trigger new concern in the waning days of the Trump administration.
Iran's defense minister vowed to continue Mohsen Fakhrizadeh’s work “with more speed and more power.”
Iran’s Supreme Leader Ayatollah Ali Khamenei said there would be a "definitive punishment of the perpetrators and those who ordered it."
The president seemed to drop the idea after top advisers warned that military action may ignite a broader conflict.
The outgoing president is purging agencies to expand his influence, and Biden's team can do little to limit Trump's behavior toward Iran, Afghanistan and more.
National security officials held a last-minute press conference to warn about foreign interference in the 2020 election.
Navid Afkari was accused of killing a man at a protest against the country's Shiite theocracy in 2018.
Jahane Sanat had published an interview with an epidemiologist who said Iran's official COVID-19 figures account for only 5% of the real toll.
Iranian officials had downplayed the fire, which could set back the country's development of advanced centrifuge models.