Iran has filed a formal complaint with the International Court of Justice (ICJ) to recover assets frozen in the United States.
The UN court in The Hague said on June 15 that the claim had been filed the day before.
In remarks broadcast on state television, President Hassan Rohani announced the government had "officially complained about America to the International Court of Justice for the confiscation and theft of $2 billion of the property of the central bank."
It was not immediately clear whether the ICJ would have jurisdiction over the case.
The U.S. Supreme Court ruled in April that the frozen assets must be turned over to American families of people killed in the 1983 bombing of a U.S. Marine Corps barracks in Beirut and other attacks blamed on Iran.
Tehran denies any role in the attacks.
Based on reporting by AFP, AP, and Reuters