"In my opinion, the decision to ban Trump was based on emotions and personal political preferences," Navalny wrote on Twitter.
He noted that the president had been writing "very irresponsible things" on the platform, but paid for it by losing reelection.
"Don't tell me he was banned for violating Twitter rules. I get death threats here every day for many years, and Twitter doesn't ban anyone (not that I ask for it)," Navalny continued. He noted that "cold-blooded murderers" like Russian President Vladimir Putin and Venezuelan President Nicolás Maduro are allowed on the platform.
LINDSEY GRAHAM CALLS TRUMP'S TWITTER BAN A MISTAKE
Navalny, the most visible opponent of Putin, was flown to Germany two days after falling ill Aug. 20 on a domestic flight in Russia. Labs determined that he was exposed to a Soviet-era Novichok nerve agent, and Navalny has since maintained that agents of Putin tried to poison him.
Navalny said there were plenty of examples of private companies such as Twitter becoming Russia and China's "best friends" and honoring censorship requests.
"This precedent will be exploited by the enemies of freedom of speech around the world. In Russia as well," said the Russian dissident. "Every time when they need to silence someone, they will say: 'This is just common practice, even Trump got blocked on Twitter'."
Navalny called on Twitter to create a committee that would handle decisions about who can and cannot tweet. "We need to know the names of the members of this committee, understand how it works, how its members vote and how we can appeal against their decisions."
Twitter also banned Trump’s campaign account "Team Trump" and the president’s allies like Gen. Michael Flynn and lawyer Sidney Powell.
Conservatives sounded the alarm that they might be the next victim of the Big Tech crackdown.
TWITTER SUSPENDS @realDonaldTrump ACCOUNT PERMANENTLY
"Twitter may ban me for this but I willingly accept that fate," Sen. Lindsey Graham, R-S.C., tweeted Saturday. "The Ayatollah can tweet, but Trump can’t. Says a lot about the people who run Twitter."
Twitter defended the ban, which followed an attack on the Capitol earlier this week that left five people dead -- including a police officer -- and a number of shaken lawmakers calling for Trump to resign or be impeached.
"After close review of recent Tweets from the @realDonaldTrump account and the context around them — specifically how they are being received and interpreted on and off Twitter — we have permanently suspended the account due to the risk of further incitement of violence," the company wrote in a blog post Friday night.
The platform temporarily locked Trump's account earlier this week -- an unprecedented move -- after dubbing several of his tweets as contributors to the Capitol siege Wednesday. Lawmakers were holding a joint session to count Electoral College ballots that confirmed Trump had ben defeated by Democratic challenger Joe Biden.
Fox News' Vandana Rambaran contributed to this report.