Israel's navy said special forces they discovered a weapons cargo after they boarded a ship 100 miles off the coast of Israel on the Mediterranean on Wednesday.
Israeli authorities said they suspected the weapons were being shipped from Iran to Syria on the Antigua-flagged vessel.
The Israeli military said the ship was intercepted during a routine patrol. After an initial search, the ship was towed to the Israeli port of Ashdod, north of Gaza.
In a statement received by Ma'an, the military said the weapons on board the ship were concealed to give the appearance of civilian cargo.
Israeli Defense Minister Ehud Barak hailed the seizure of the ship as "another success in the endless struggle against attempts to smuggle weapons and military equipment whose goal is to strengthen terrorist elements who threaten the security of Israel."
Israeli news reports compared the operation to the January 2002 commando raid on the freighter Karine-A, which Israel said contained a massive shipment of weapons for Palestinian militias at the height of the second Intifada.