The patrol ship USS Sirocco intercepted and seized the shipment hidden aboard a small dhow on March 28.
The illicit cargo included 1,500 AK-47s, 200 RPG launchers and 21.50 caliber machine guns, the Navy said in a statement.
The dhow and its crew were allowed to sail on after the weapons were seized.
The Navy said it was the latest in a series of illicit weapons shipments which the United States believes originated in Iran.
The warring parties are preparing for a UN-brokered ceasefire due to take effect on April 10 and intended to pave the way for peace talks in Kuwait a week later.