No War Against Iran Act This bill prohibits the obligation or expenditure of federal funds for any use of military force in or against Iran unless Congress has either declared war or enacted specific statutory authorization for such use. An exception is made for a presidential exercise of power to introduce Armed Forces into hostilities (or situations where imminent involvement in hostilities is clearly indicated) when there is a national emergency created by an attack upon the United States. The bill further states that no prior authorizations of military force (e.g., against Iraq) may be construed to authorize the use of military force against Iran.