US President Joe Biden welcomed the returning prisoners home but his administration also announced fresh US sanctions.
The New York Times reported that a Swedish citizen, who according to the paper has been working for the European Union's diplomatic corps, had been imprisoned in Iran for more than 500 days.
US envoy for Iran, Abram Paley, met on Friday with the family of Sharmahd, who was convicted of heading a pro-monarchist group accused of a deadly bombing in 2008.
The pardon approved by Ayatollah Ali Khamenei came with conditions which said the measure would not apply to any of the numerous dual nationals held in Iran.
Farhad Meysami has been jailed since 2018 for supporting women activists protesting against the headscarf police.
In the 120 days since the protests on 2022, Iran has ruthlessly murdered at least 525 protesters and detained and tortured countless more.