A senior lawmaker called it "hysteria." The Foreign Ministry said it was "media vandalism." And the Kremlin lamented the "emotional atmosphere" currently in Washington about Attorney General Jeff Sessions' meetings with a Russian diplomat, saying it could thwart efforts to mend relations.
The uproar is widely seen in Moscow as part of efforts by President Donald Trump's political foes to block any possible attempts at a rapprochement with Russia.
President Vladimir Putin's spokesman Dmitry Peskov told reporters he did not know anything about the meetings last year between Ambassador Sergei Kislyak and Sessions, who at that time was a U.S. senator. Sessions also was a policy adviser to Trump's campaign.
News of the two meetings has spurred calls in Congress for Sessions to recuse himself from an investigation into alleged Russian interference in the U.S. presidential election. Sessions' office has said the meetings were in his capacity as a senator rather than as a Trump campaign adviser.
Peskov argued it was normal for an ambassador to meet with officials and lawmakers, adding that "the more such meetings an ambassador has, the more efficient his work is."
Asked if the accusations against Sessions smacked of McCarthyism, he answered cautiously that it's not the Kremlin's job to make judgments about U.S. domestic policy.
Peskov described the reaction to the news of the Sessions' meetings as "an emotional atmosphere leading to resistance to the idea of any U.S.-Russia dialogue."
"The negative effect for the idea to develop at least some dialogue with Russia is evident," he added.
Foreign Ministry spokeswoman Maria Zakharova, was more combative, denouncing what she described as the U.S. "media vandalism."
"Let me open a military secret for you: It's part of the diplomatic job to have contacts in the country they are posted to," she said sarcastically. "It's their obligation to meet with officials and members of the political establishment."
Zakharova also drew a literary allusion to George Orwell's "1984."
"The media in the United States have become such a Big Brother, moving far beyond professional ethics and their own competence, raising accusations and passing judgments by fabricating false information," she said.
Alexei Pushkov, the head of the information policy committee in the upper house of the Russian parliament, described Democrats' demands for Sessions' resignation as a "borderless paranoia."
"Hysteria in the U.S. has driven politicians into a trap," Pushkov tweeted. "You met a Russian? That's an end to your career. You concealed it? You go to prison. The spirit of Joseph McCarthy has been waiting for its hour to come."
Trump has repeatedly said he wants to improve relations with Russia, but Moscow appears increasingly frustrated by the lack of visible progress, as well as by the support from Trump administration officials for continuing sanctions imposed on Russia for its interference in Ukraine.
Most Russian observers and news media cast the news over Trump's alleged links with Russia as attempts by the Democrats to undermine the Republican's agenda.
Fyodor Lukyanov, the head of the Council for Foreign and Defence Policies, a group of leading Russian foreign policy experts, said "the highest level of paranoia vis-a-vis Russia" in the U.S. makes any thaw in relations unlikely.
"The whole hysteria in the United States around Russia and the unprecedented presence of Russian issue and Russian factor in the U.S. domestic politics to me has one particular aim: to limit any space for manoeuvring for President Trump in a relationship with Russia as much as possible, not to allow him to change the nature of relationship," Lukyanov said.
"From this point of view their efforts are successful, because we see that his tone is changing," he added.
Lukyanov ridiculed the portrayal of Russia as a "kingmaker everywhere in the world" and deplored what he called a "self-defeating and self-destructive approach" by the U.S. establishment.
"Everything we hear isn't harming Russia that much but is harming the credibility of the United States," he said. "If Americans themselves believe that countries and leaders outside the U.S. can decide how they vote, that's very bad."