The US president accused the NIH expert of playing "all sides of the equation" and called Fauci's warnings about reopening too early "not an acceptable answer."
The demonstrations occurred in US states where Republican governors have started reopening businesses during the coronavirus pandemic.
Trump Says Coronavirus 'Will Go Away Without A Vaccine', Contradicting Top Health Official (And Himself)
The US president said just days ago that the US "needs the vaccine".
The US president admitted that medical experts would discourage him from making such remarks.
Pitt bashes Donald Trump, then thanks Fauci for his "calm" and his "clarity in this unnerving time."
The retweet came hours after Fauci suggested earlier action could have saved lives from COVID-19.
"Mr. President, many people will die," he was told by Dr. Anthony Fauci, according to The Washington Post.
Dr. David Nabarro said outbreaks are likely to continue for "a long time to come" and advised countries to focus on detecting and isolating cases.
Despite saying Saturday the worst was yet to come, the president talked of opening things back up: "We don’t want to be doing this for months and months.”
Trump’s top health adviser Dr. Anthony Fauci warned that the US death toll could hit 200,000.