Google is to "derank" stories from Kremlin-owned publications Russia Today (RT) and Sputnik in response to allegations about election meddling by President Putin's government.
Alphabet chairman Eric Schmidt said the search giant needed to deal with the spread of misinformation.
RT has been described by US intelligence agencies as "Russia's state-run propaganda machine".
The publications said the move was a form of censorship.
Speaking at the Halifax International Security Forum, Mr Schmidt said: "We're well aware of this one, and we're working on detecting this kind of scenario you're describing and deranking those kinds of sites."
He then named two of Russia's biggest media outlets: RT, a TV and online news organisation, and Sputnik, an online media network.
"I am strongly not in favour of censorship. I am very strongly in favour of ranking. It's what we do," he added. "It's a very legitimate question as to how we rank, A or B, right? And we do the best we can in millions and millions of rankings every day," said Mr Schmidt.
But he added that it was a constant tug-of-war altering the search giant's algorithms to detect "weaponised" information because those seeking to manipulate the news agenda "will get better tools too".
The comments drew an angry response from the two publications, which have always defended themselves as legitimate news organisations.
"Good to have Google on record as defying all logic and reason: facts aren't allowed if they come from RT, 'because Russia' - even if we have Google on Congressional record saying they've found no manipulation of their platform or policy violations by RT," Sputnik and RT editor-in-chief Margarita Simonyan said in a statement published on RT.
In October, Twitter announced that it would no longer allow advertisements from RT and Sputnik.
And in November, RT was forced to register itself as a '"foreign agent" by the US Department of Justice. The broadcaster is fighting the order in court.
Russia has repeatedly denied claims that it interfered in the 2016 presidential elections. US intelligence services accuse the country of trying to sway the vote in favour of Donald Trump by spreading fake news and hacking the Democratic National Committee (DNC) networks in order to undermine Hillary Clinton.