YouTube, Instagram and TikTok, according to Russian media authority Roskomnadzor, are partially responding to requests to remove calls for protests in support of opposition leader Alexei Navalny.
In Moscow, Vladivostok and Omsk, among others, hundreds of people took to the streets on Saturday to express their support for Navalny.
Navalny was arrested on Sunday on his return to Russia.
President Vladimir Putin's most prominent critic has spent the past few months in Germany to recover from his poisoning with the nerve agent novichok.
Russia called on social media to remove calls for protests.
The country has had a law since 2018 that prohibits the summoning of minors to participate in illegal street protests.
According to Roskomnadzor, TikTok had deleted 38 percent of illegal calls on Friday.
YouTube and the locally popular VKontakte would have removed half of the messages, and Instagram 17 percent.
The media authority is formally opposed to the calls because demonstrations would be dangerous for minors.
The Kremlin calls the measures "fully justified".
At 11.30 am (Dutch time) it was announced that at least 230 people had been arrested in the protests in various Russian cities.
The demonstrations started in Eastern Russia, where the time difference with Moscow is seven hours.