The country is holding parliamentary elections later this month, with nearly all vocal Kremlin critics including Navalny’s allies barred from running.
Last month Russian communications watchdog Roskomnadzor demanded that Google and Apple remove Navalny’s app from their stores.
On Thursday, Roskomnadzor ramped up pressure on the Western tech giants by saying they could be held criminally liable if they continue to refuse to comply with Russian law.
“Criminal liability is foreseen for organising as well as taking part in the work of extremist organisations banned in Russia,” the media watchdog said in a statement carried by Russian news agencies.
Roskomnadzor did not immediately provide a comment when contacted by AFP.
Earlier this year, opposition leader Navalny saw his organisations declared “extremist” and banned in the country, while all of his top aides have fled.
The media regulator then barred dozens of websites linked to Navalny including his main website navalny.com.
In a message from prison, Navalny has urged supporters to download an app that aims to help Russians to vote out candidates from the ruling United Russia party in the upcoming polls.
The “Smart Voting” tactic has seen the increasingly unpopular United Russia party lose a number of seats in recent local elections.
“If something can be called ‘interference in Russian elections’, it is the attempts of Roskomnadzor to block the Smart Voting app,” Navalny’s spokeswoman Kira Yarmysh said on Twitter. “Download them asap.”