According to the Chicago Tribune
report the country's Navy commander, Rear Admiral Habibollah Sayyari, said such deployments around the world would protect Iranian merchant vessels which may face danger in the Gulf of Aden and the northern part of the Indian Ocean. The main danger in the region to merchant ships at present is bands of Somali pirates who have frequently hijacked commercial vessels in order to extract bribes for hostages.
Rear Admiral Sayyari was quoted as stating that "our presence in international waters is aimed at safeguarding the interests of the Islamic Republic and strengthening military power to defend Iran."
The Iranian Navy is primarily made up of naval frigates (some of which are British made and were bought by the Shah of Iran back in the 1970s), patrol boats, a small fleet of submarines (mostly Russian made Kilo diesel powered ones) and various smaller fast attack crafts, and missile boats operated primarily by the Iranian Revolutionary Guard Corps (a helpful pennant list can be found here
Whilst it has substantially improved since the end of the horrific Iran-Iraq War in 1988 -- after two of its frigates were taken out of action by the U.S. Navy in rapid succession during Operation Praying Mantis -- the Iranian Navy continues to remain for all intents and purposes a green-water navy tasked with defending Iran and her territorial waters.
The new vessels that are being planned to increase the size of Iran's navy attest to this tangible reality. They are predominately destroyers and frigates armed with ship to ship missiles which would be suitable for defending the narrow confines of the Persian Gulf rather than projecting substantial Iranian power over the horizon.
Last February the Iranian Navy crossed the Suez Canal
(it had previously done so for the very first time since 1979 last year) following a journey to Syria its -- under the present regime in Damascus -- primary ally in the region.