Navies from Iran's armed forces and Revolutionary Guards are taking part in the "2022 Marine Security Belt" exercise over an area of 17,000 square kilometers (6,560 square miles), Rear Admiral Mostafa Tajoldini, spokesman for the drills, told state TV.
The drills will include various tactical exercises such as rescuing a burning vessel, releasing a hijacked vessel, and shooting at air targets at night.
He said the exercises began in the early hours of Friday morning.
The three countries started joint naval drills in 2019 in the Indian Ocean and the Sea of Oman area, Tajoldini said.
"The purpose of this drill is to strengthen security and its foundations in the region, and to expand multilateral cooperation between the three countries to jointly support world peace, maritime security and create a maritime community with a common future," Tajoldini said.
Since coming to office last June, Iran's hardline President Ebrahim Raisi has pursued a "look east" policy to deepen ties with China and Russia. Tehran joined the Shanghai Cooperation Organisation in September, a central Asian security body led by Beijing and Moscow.
Foreign Minister Hossein Amirabdollahian visited China last week and Iran's president met his Russian counterpart in Moscow on Thursday.