The Russian leader was "understanding" of the concerns expressed by Cameron in a phone call on Tuesday, said a spokeswoman for the prime minister's Downing Street office yesterday.
Thirty crew members from around the world, including six Britons, were arrested in September when two activists tried to scale a state-owned Gazprom oil rig in the Barents Sea.
"The prime minister raised the case of the Greenpeace activists detained in Russia and the need for prompt, fair and proportionate action by the Russian judicial system," the spokeswoman said.
Cameron's intervention comes after relatives and supporters of British crew member Kieron Bryan, 29, held a silent protest outside the Russian embassy in London on Saturday.
An international maritime court in the German city of Hamburg began hearing on Wednesday a Dutch complaint over Russia's detention of the Netherlands-flagged ship, the Arctic Sunrise.