The intelligence official alleged the protests had been "pre-planned" and that foreign powers had a role in provoking the riots.
It was not immediately clear when the Germans were detained. There was no immediate comment from Berlin.
At least eight people died in clashes between security forces and opposition supporters across Iran last month. It was the worst bloodshed since the height of the protests following the disputed re-election of President Mahmoud Ahmadinejad last summer.