Iran often stages exercises or tests weapons to show its determination to counter any attack by the United States or Israel against sites they believe are to make nuclear arms.
"The aim of this manoeuvre is to increase the level of readiness of Iran's naval forces and also to test and to use domestically-made naval weaponry," Admiral Qasem Rostamabadi told state radio.
The radio said the naval manoeuvres would cover an area of 50,000 square miles, including the Sea of Oman off Iran's southern coast.
"In this six-day long manoeuvre there will be more than 60 combat vessel units," Admiral Habibollah Sayyari, commander of the navy, was quoted as saying by the Kayhan daily.
They would include destroyers, missile-equipped battleships, submarines, special-operations teams, helicopters, and fighter planes, he said.
Iran, the world's fourth-largest crude oil producer, says its uranium enrichment activities are aimed at making fuel for electricity-generating nuclear power plants, not bombs.
The United States says it wants diplomacy to end the nuclear row, but neither Washington nor Israel have ruled out military action if that fails. Iran has vowed to retaliate if pushed.
Military analysts say Iran's real ability to respond could be with more unconventional tactics, such as deploying small hit-and-run craft to attack oil tankers, or using allies in the Middle East to strike at U.S. or Israeli interests.
Iran has previously said it could close the Strait of Hormuz to shipping, through which about 40 percent of the world's globally traded oil passes. The United States has pledged to protect shipping routes.
An Iranian naval commander was last week quoted as saying the country's navy could strike an enemy well beyond its shores and as far away as Bab al-Mandab, the southern entrance to the Red Sea that leads to the Suez Canal.
Iran's 1980s war with Iraq included a period that became known as the tanker war when oil carriers and other energy installations became targets by both sides. This led to the United States stepping in to protect oil shipping.
(Reporting by Parisa Hafezi and Hashem Kalantari; Writing by Fredrik Dahl; Editing by Katie Nguyen)
