"The Iranian oil tanker was attacked by 35 pirate boats on Sunday afternoon," Iranian Navy Deputy Commander Rear Admiral Seyyed Mahmoud Mousavi said.
He added that the Iranian warships patrolling the area rushed to the aid of the oil tanker upon receiving its distress call, which reported an unauthorized boarding attempt by several people.
No injuries were reported among the crews of the Iranian ships.
In line with international efforts against piracy, Iran's Navy has been conducting anti-piracy patrols in the Gulf of Aden since November 2008 to safeguard maritime trade and in particular ships and oil tankers owned or leased by Iran.
Last May, International Maritime Organization (IMO) Secretary General Efthimios E. Mitropoulos described the anti-piracy efforts by Iran's Navy as "effective."
The Gulf of Aden, which links the Indian Ocean with the Suez Canal and the Mediterranean Sea, is the quickest route for thousands of vessels traveling annually between Asia, Europe and the Americas.
However, attacks by heavily armed Somali pirates on speedboats have prompted some of the world's largest shipping firms to switch routes from the Suez Canal and reroute cargo vessels around southern Africa, leading to climbing shipping costs.
Somalia has been without a functioning government since 1991, when warlords overthrew former dictator Mohamed Siad Barre.
Iran Navy saves oil tanker from pirates
Iran's Navy warships have foiled a pirate attack on an Iranian oil tanker close to the Bab el-Mandeb strait, which connects the Red Sea to the Gulf of Aden off the coast of lawless Somalia, Press TV reported.