Assadollah Assadi, a diplomat posted to Austria, was arrested in Germany after the opposition People's Mujahedin (MEK) accused him of being the organiser of the alleged plot to bomb their annual conference at Villepinte, near Paris.
Former New York mayor Rudy Giuliani, who is now US President Donald Trump's lawyer, former US Speaker of the House Newt Gingrich and former French foreign minister Bernard Kouchner attended the meeting.
The Berlin court on Monday ruled that Assadi did not enjoy diplomatic immunity because he was on holiday outside the country where he was posted and agreed to Belgium's extradition request.
Belgian prosecutors in July announced that they had uncovered the alleged plot after arresting two Belgian nationals of Iranian origin with 500 grammes of TATP, a highly unstable explosive, in their car.
A fourth suspect was arrested in France over the summer and handed over to Belgium.
Iran accused the MEK of mounting the plot themselves.
The case has led to diplomatic tensions between Tehran and European countries that are trying to save the Iran nuclear accord, despite Trump's decision to withdraw the US from it.