(CNN) -- How many young people have gotten in trouble for something they've posted on Facebook? Maybe a party picture or an offensive comment compromised their chances at a job.

But a 25-year-old Iranian says his Facebook activity has led to his father's detention in a notorious prison in Tehran. And now he's struggling to find a way to free him.

"I want my family to forgive me," Yashar Khameneh said. "But I believe what I believe in."