Iran has imposed sanctions on dozens of US citizens, many of them from the military, over the 2020 killing of General Qassem Soleimani in a drone strike.
Iran's Foreign Ministry said the 51 US citizens had been targeted for what it called "terrorism" and human rights violations.
The step lets Iranian authorities seize any assets they hold in Iran but the apparent absence of such assets means it will likely be symbolic.
The ministry said in a statement carried by local media that the 51 had been targeted for "their role in the terrorist crime by the United States against the martyred General Qassem Soleimani and his companions and the promotion of terrorism and violations of fundamental human rights".
Soleimani - the commander of Iran's Quds Force, the overseas arm of the elite Revolutionary Guards - was killed in Iraq in a drone strike on January 3, 2020, ordered by then-president Donald Trump.
Those added to Iran's sanctions list included US General Mark Milley, chairman of the Joint Chiefs of Staff and former White House national security adviser Robert O'Brien.
In a similar move announced a year ago, Iran imposed sanctions on Trump and several senior US officials over what it called "terrorist and anti-human rights" acts.
Iranian President Ebrahim Raisi, speaking on the second anniversary of Soleimani's assassination, said this week Trump and former Secretary of State Mike Pompeo must face trial for the killing.
Australian Associated Press
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