The second activist said security forces had forbidden Geravand's parents from posting her picture on social media or from talking to human rights groups.
The head of the Tehran Metro Operating Company, Masoud Dorosti, told IRNA the CCTV footage showed no sign of verbal or physical conflict between passengers or company employees.
An Iranian journalist was briefly arrested on Monday when she went to the hospital to inquire about Geravand's situation, Iranian media reported.
"Iranian security institutions have said her condition was caused by low pressure - an oft-repeated scenario from such institutions," Iran-based rights group Dadban said on social media.
Germany's Foreign Minister Annalena Baerbock on social media platform X said: "Once again a young woman in #Iran is fighting for her life.
Persons:
Armita, Mahsa, Geravand, Hengaw, Masoud Dorosti, Dadban, IRNA, Annalena Baerbock, Michael Georgy, William Maclean
Organizations:
Reuters, Care Unit, Tehran Metro Operating Company, Dubai Newsroom, Thomson
Locations:
DUBAI, Iranian, Tehran, Iran