This is the third joint naval drill between the countries since 2019 as Tehran and Moscow seek to step up military cooperation with Beijing amid regional tensions with Washington.
Iran, Russia and China have started a joint naval drill in the Indian Ocean aimed at boosting marine security.
Iran's state TV said on Friday 11 of its vessels were joined by three Russian ships including a destroyer, and two Chinese vessels.
Iran's Revolutionary Guard will also participate with smaller ships and helicopters.
The report said the manoeuvres would cover some 17,000 square kilometres, or 10,600 miles, in the Indian Ocean's north, and include night fighting, rescue operations and firefighting drills.
It coincided with a recent visit by Iranian President Ebrahim Raisi to Russia that ended on Thursday.
“Improving bilateral relations between Tehran and Moscow will enhance security for the region and the international arena,” Raisi said upon returning from Russia on Friday, the official IRNA news agency reported.
Tehran has sought to step up military cooperation with Beijing and Moscow amid regional tensions with the United States.
Visits to Iran by Russian and Chinese naval representatives have also increased in recent years.
Iran has been holding regular military drills in recent months, as attempts to revive its 2015 nuclear deal with world powers flounder.
Russia is also at loggerheads with the US and the West over its neighbour Ukraine, where it has sent some 100,000 troops that Washington, Kiev and their allies fear will be used to invade the country.
Russia on Thursday announced sweeping naval manoeuvres in multiple areas involving the bulk of its naval potential, over 140 warships and more than 60 aircraft, to last through February.