"While we recognise that governments have a responsibility to bring to justice those who commit crimes, this must be done according to international standards for fair trial," said Malcolm Smart, Amnesty International's Middle East and North Africa director.
"It is clear that Habibollah Latifi did not receive a fair trial by international standards, which makes the news of his impending execution all the more abhorrent."
Habibollah Latifi was sentenced to death in 2008 for waging war against God (mohareb) by committing acts of violence as a member of the Party of Free Life of Kurdistan (PJAK) in Iran's western province of Kordestan in 2007.
His death sentence was upheld by an appeals court in 2009.
The law student admitted being a PJAK supporter but denied committing any violence, his lawyer says.
He says that the execution is scheduled at a prison in Sanandaj - the capital of Kordestan - early on Sunday.