Mr. Soltani, 26, was arrested last month as Iran brutally repressed anti-government demonstrations.
Mehdi Mahmoudian, co-writer of “It Was Just an Accident,” was one of several people detained after signing a letter objecting to the crackdown on protests.
An Iranian government official said some children had been detained, the first such acknowledgment in weeks of anti-government protests.
“He went out for freedom,” said the cousin of one of those who was killed when Iranian authorities mounted a deadly crackdown on protests across the country.
Protests that erupted late last year shook elements of the Iranian government, according to the reports.
Protests erupted amid a communications blackout. But as video and witness accounts trickle out, the brutality of the regime’s crackdown is becoming clear.
The bloody crackdown offers hints about growing tensions inside the country’s ruling system as the cleric’s rule comes under strain.
President Trump said the United States was “watching Iran” and sending a naval force there, despite also saying that his threats had halted executions.
Witness testimony and videos from Tehran’s largest cemetery show disrespectful treatment of the dead after a brutal government crackdown.
After a crackdown that killed thousands, Iran’s prosecutor general said on Wednesday that “the sedition is over now,” vowing to punish those responsible for the protests.