The statement showed an image of a young boy carrying an assault rifle and gave no further details.
It is not the first time Iranian state agents have been investigated or accused of plots in Europe.
This follows allegations that Iran tried to harm the former PM while he was abroad.
Accompanied by a major Russian aerial bombing campaign, Syrian pro-government forces have marched swiftly into insurgent territory in Deraa province over the past two weeks.
It would be the first instance in which the US government lists an official state military as a foreign terrorist organization.
The British Museum is slated to open a major exhibition of Assyrian artifacts as experts warn that ISIS-looted items is still a problem.
"Iran considers the Zionist regime illegitimate and its actions in the region aggressive and condemnatory."
The battles have pushed more than 270,000 people out of their homes.
Rouhani also said U.S. attempts to pressure its allies to stop buying Iranian oil exports are "exaggerated" and could never be put in place.
The diplomat was arrested for allegedly plotting to plant a bomb at a meeting in which Rudy Giuliani was expected to attend.
“Iran, North Korea, Syria and Pakistan are making efforts to expand their conventional weapons arsenal through the production of weapons of mass destruction,” the Bavarian intelligence agency said.