"They're killing people," he said.
As the president was leaving the White House for Camp David on Friday afternoon, he was asked, specifically, "On COVID misinformation, what's your message to platforms like Facebook?"
Biden answered, "They're killing people. I mean, it really -- look, the only pandemic we have is among the unvaccinated. And they're killing people."
It was the only question Biden took before boarding Marine One to leave town for the weekend and follows comments by other Biden administration officials warning of the dangers of misinformation in combatting COVID-19.
On Thursday, Surgeon General Vivek Murthy issued the first public health advisory of the Biden administration to addresses an epidemic of misinformation and disinformation and its harmful impact on public health. The Biden administration is now calling on social media companies to take further action to combat misinformation around the COVID-19 vaccine.
Ahead of Biden's departure, White House press secretary Jen Psaki was pressed Friday by ABC News Congressional Correspondent Rachel Scott over whether Facebook was doing enough to combat the issue.
"Clearly not," Psaki said, "because we're talking about additional steps that should be taken."
"We're dealing with a life-or-death issue here. And so, everybody has a role to play in making sure there's accurate information," she added. "It's clear there are more that can be taken."
Facebook took issue with the description by the president, saying in a statement that his claim was not true.
"We will not be distracted by accusations which aren't supported by the facts," Facebook spokesperson Dani Lever said in a statement to ABC News. "The fact is that more than 2 billion people have viewed authoritative information about COVID-19 and vaccines on Facebook, which is more than any other place on the internet. More than 3.3 million Americans have also used our vaccine finder tool to find out where and how to get a vaccine. The facts show that Facebook is helping save lives. Period."
It also comes amid the government's current push to boost stalling vaccination rates while the delta variant takes hold of the country's unvaccinated, in what Centers for Disease Control and Prevention Director Dr. Rochelle Walensky called "a pandemic of the unvaccinated" on Friday.
The Biden administration has doubled down on their efforts to get more people vaccinated -- particularly after the country missed the president's goal of getting 70% of adults with at least one dose by July 4.
The surgeon general's new advisory specifically digs into social media platforms as having greatly contributed to the "unprecedented speed and scale" of misinformation's spread and Murthy calls on technology and social media companies to "take more responsibility to stop online spread of health misinformation."
It argues that misinformation, particularly on social media websites like Facebook, has hindered vaccination efforts, sown mistrust, caused people to reject public health measures, use unproven treatments, prolonged the pandemic and put lives at risk.
"Simply put, health misinformation has cost us lives," Murthy said from the White House Thursday.
ABC News' Sasha Pezenik, Molly Nagle and Justin Gomez contributed to this report.