U.S. President Joe Biden said Friday social media platforms like Facebook are "killing people" with misinformation surrounding the COVID-19 pandemic as the White House ramps up its rhetoric around false information on social media regarding the pandemic.

"They're killing people -- I mean they're really, look, the only pandemic we have is among the unvaccinated," Biden told reporters as he left the White House for Camp David. "And they're killing people."

U.S. Surgeon General Dr. Vivek Murthy warned Thursday health misinformation is "a serious threat to public health," and the administration directly called out social media giant Facebook for not doing enough to stop the spread of false information on its platform. Meetings between the Biden administration and Facebook in recent weeks have been "tense," a source familiar with the conversations told CNN.

The source said Biden officials who had taken concerns about vaccine misinformation to Facebook had concluded that the company was either not "taking this very seriously, or they are hiding something," due to what they view as Facebook's unwillingness to tackle vaccine misinformation.

A Facebook spokesperson did not directly respond to the source's characterization of the company's efforts but told CNN that Facebook is working to tackle COVID-19 misinformation and has launched initiatives like a vaccine appointment tool.

Earlier Friday, White House press secretary Jen Psaki blasted social media platforms for taking insufficient action on misinformation.

"Why don't we all participate in a process that will help provide accurate information out there?" Psaki said.

The White House doesn't find Facebook's response and information sharing surrounding vaccine misinformation sufficient, Psaki said Friday.

On Thursday, Psaki cited four actions the administration wants social media platforms to take: measure and publicly share the impact of misinformation on their platform, implement a more robust enforcement strategy, take faster action against harmful posts and promote quality information in their feed algorithm.

Asked by CNN's Phil Mattingly on Friday to elaborate on the requests and whether Facebook has been amenable to the requests, Psaki explained that the White House is in regular touch with social media platforms.

"We are regularly making sure social media platforms are aware of the latest narratives dangerous to public health that we and many other Americans are seeing across all of social and traditional media," she said.