Acosta had been questioning Trump about his claim that a caravan of migrants posed a threat to the US when the president turned on the journalist.
CNN and other White House reporters defended Acosta, saying there was nothing wrong with his questioning of Trump and that he did not inappropriately touch the assistant.
In response, Sanders said the White House ban on Acosta's credentials would stand.
The whole thing seemed to be over until later that afternoon when White House Press Secretary Sarah Huckabee Sanders announced that Acosta's press credentials had been revoked because he placed "his hands on a young woman just trying to do her job". When he tried to follow up with another question, Trump said, "That's enough!" and a female White House aide unsuccessfully tried to grab the microphone from him.
The president and the reporter sparred at a press briefing Wednesday, culminating with a White House intern trying to pull the microphone away from Mr Acosta. "This conduct is absolutely unacceptable", Sanders wrote Wednesday night. It is also completely disrespectful to the reporter's colleagues not to allow them an opportunity to ask a question.
It also would not explain why press officers managing Wednesday's news conference asked the intern to try to wrestle the microphone away from Acosta, rather than just turning it off remotely from the board that controls the audio.
"I'm not a fan of yours either".
Sanders used a 15 second video clip that appeared to have been significantly manipulated to prove her accusation.
"This President's ongoing attacks on the press have gone too far".
In an interview with Fox News on Thursday, senior White House communications advisor Mercedes Schlapp insisted that the intern was "shaken up" and "intimidated" by Acosta and added "what we are seeing is bad behavior that can not be tolerated".
So, as the president said that the question was racist, and I - he was literally having white nationalists at the White House.
"I worked with Jim @Acosta at CNN".
Knox added "We urge the White House to immediately reverse this weak and misguided action". Trump shouted him down. "We stand by our statement".
Margaret Talev, senior White House correspondent for Bloomberg News, and board member and past president of the White House Correspondents Association, weighed in on these events when she joined On Point Thursday. But a frame-by-frame comparison with an Associated Press video of the same incident shows that the one tweeted by Sanders appears to have been altered to speed up Acosta's arm movement as he touches the intern's arm, according to Abba Shapiro, an independent video producer who examined the footage at AP's request.