The Spanish company also planned to illegally export military aircraft parts to Venezuela, according to police.
The materiel intended for Venezuela was found along with the nine Bell-112 helicopters at warehouses in Madrid and Barcelona. Authorities valued the merchandise at roughly 100 million euros ($140 million).
Made in the United States, the Bell-212 has a maximum speed of 230 kph (143 mph) and can fly 600 kilometers (373 miles) without refueling.
The Bell helicopters, used to transport troops and military equipment, are subject to export controls under both Spanish and European Union regulations, police said.
Given the impossibility that the Spanish government would approve the sale of the choppers to Iran, the vendors sought to circumvent the restrictions through subterfuge.
Investigators were alerted to the transaction when the Iranian buyers arrived in Spain.