No group immediately claimed responsibility for the attack. Rahmatabadi, whose portfolion included mining and commerce, was not a well-known public figure. He had served a similar role under the country's previous president Mahmoud Ahmadinejad.
This was the second attack in recent days on a government official in Iran. On Wednesday, a gunman killed an Iranian state prosecutor in a restive south-eastern province of Sistan Baluchistan, near the country's border with Pakistan.