On Thursday morning, while MSNBC's "Morning Joe" was on the air, Trump posted a pair of shocking tweets about Brzezinski and co-host Joe Scarborough.
He said the show is "poorly rated" and that the hosts "speak badly of me." He then called them disparaging names and claimed they courted him for an interview at Mar-a-Lago around New Year's Eve.
"She was bleeding badly from a face-lift. I said no!" the President wrote.
When asked about it during a House Republicans news conference, House Speaker Paul Ryan responded, "Obviously I don't see that as an appropriate comment."
He added: "What we're trying to do around here is improve the tone, the civility of the debate. And this obviously doesn't help do that."
Other Republican lawmakers reacted by making public pleas to the President to stop the personal attacks.
"Please just stop. This isn't normal and it's beneath the dignity of your office," GOP Sen. Ben Sasse tweeted shortly after Trump launched into a tweetstorm about the show.
Republican Sen. Lisa Murkowski of Alaska tweeted to Trump, "do you want to be remembered for your tweets or your accomplishments?"
She also tweeted, "Stop it! The Presidential platform should be used for more than bringing people down."
Sen. Lindsey Graham, who is a strong critic of the Trump administration, tweeted, "Mr. President, your tweet was beneath the office and represents what is wrong with American politics, not the greatness of America."
Rep. Lynn Jenkins, R-Kansas, tweeted: "This is not okay. As a female in politics I am often criticized for my looks. We should be working to empower women."
She later told CNN she was "extremely disappointed."
"That's not OK," she said. "It's just not acceptable. We need to demand better of folks in positions like myself, the President ... We should just appreciate if the President could focus with us on doing some really good things for the American people and leave comments like that to himself."
GOP Sen. Orrin Hatch didn't directly acknowledge Trump's remarks but tweeted an article where he is quoted saying, "It's incumbent on all of us, then — from the President to Congress on down — to be responsible for our speech."
GOP Sen. Susan Collins of Maine tweeted, "This has to stop -- we all have a job -- 3 branches of gov't and media. We don't have to get along, but we must show respect and civility."
Later Thursday, she said on MSNBC that Trump's tweet was "completely inappropriate."
"We're not going to get along, but we have to treat each other with respect and civility," she said. "The President's tweet was completely inappropriate. I think he needs to better appreciate the roles played by the three branches of government and by the media. We're not going to agree. We're not always going to get along. But there's no need for such uncivil language."
Rep. Tom Reed, R-New York, told CNN in an interview that he was "concerned with that type of language."
"Well, obviously, I was just made aware of that tweet. I don't know the context of the exchange. But obviously, I'm concerned about that type of language," he said on CNN. "Maybe the intent is to distract from the health care debate. But I want to be part of the debate that's impacting the American people."
The White House said Thursday that Trump was responding to liberal bullying when he tweeted about the MSNBC host.
"I don't think that the President's ever been someone who gets attacked and doesn't push back," deputy White House press secretary Sarah Huckabee Sanders said on Fox News. "There have been an outrageous number of personal attacks not just to him but people around him."
"This is a President who fights fire with fire and certainly will not be bullied," Sanders said.
Democrats quickly condemned the tweets as well, with House Minority Leader Nancy Pelosi asking, "I just don't know why Republicans, they can tolerate almost anything."
Speaking at a news conference, she added, "The tweets from our President, they set a low standard for public officials in terms of their demeanor. It's really sad, though."
Sen. Chris Murphy of Connecticut tweeted, "(Trump) mocks people (with) mental illness. Cheerleads effort to end their insurance. Not sure how much more monstrous this can get."
Sen. Kirsten Gillibrand tweeted, "This is not okay, Mr. President," later adding, "Since our President clearly has a problem with women, let's send more to Congress. Women of America, you need to run! RT if you agree."
Sen. Brian Schatz of Hawaii tweeted, "If anyone on my staff did this they would be fired instantly."
And Rep. Barbara Lee, D-California, tweeted a thread that began, "I want my GOP colleagues to explain to my 3 granddaughters why they think these viciously sexist comments are acceptable from our President."