"They thought that by doing so they could keep me quiet.
"After three weeks they realized that there was no point and I wasn't going to stay quiet. So they let her go."
Noushin was arrested during days of protests in opposition to the Iranian government from December 27.
At least eight people were killed in the demonstrations which Tehran said were instigated by its foreign enemies - in particular the US, Israel and the UK.
The protests, which led to street battles between demonstrators and police, coincided with Ashoura, Shia Islam's holiest event.
They follow unrest which began after presidential elections last June, which many have said were stolen by President Mahmoud Ahmadinejad.