The White House issued an emailed statement after a spokesman for the House of Representatives committee holding the hearing said the panel had been informed by Trump administration officials that Fauci had been blocked from testifying.
"While the Trump administration continues its whole-of-government response to COVID-19, including safely opening up America again and expediting vaccine development, it is counter-productive to have the very individuals involved in those efforts appearing at congressional hearings," White House spokesman Judd Deere said in a statement. "We are committed to working with Congress to offer testimony at the appropriate time."
Fauci's testimony was being sought for a May 6 hearing by a House Appropriations subcommittee that oversees health programs, said spokesman Evan Hollander. The Washington Post first reported that Fauci would not testify.
Fauci, director of the National Institute of Allergy and Infectious Diseases, has been one of the leading medical experts helping to guide the US response to the highly contagious virus that has swept across the United States.
Trump has repeatedly clashed with the Democratic-controlled House over its moves to investigate his actions or those of his administration.
In recent days, House Speaker Nancy Pelosi and Senate Democratic leader Chuck Schumer have urged wide-ranging investigations into Trump's handling of the coronavirus outbreak, which has killed tens of thousands of Americans.
Democrats have criticized Trump, saying he has failed to develop a comprehensive and effective plan for testing Americans for the coronavirus and tracing contacts of those who are infected by the virus that causes the sometimes fatal COVID-19 respiratory disease.
Fauci, 79, has had a respectful but sometimes complicated relationship with Trump.
The well-regarded doctor has at times corrected or contradicted the president at White House briefings or in press interviews on issues such as the time required to develop a vaccine and the likelihood that the coronavirus will return in the fall.
Trump has occasionally shown exasperation with Fauci but ultimately has followed, largely, the advice that he and Dr. Deborah Birx, the White House’s coronavirus task force coordinator, have provided on responding to the pandemic.
Last month, the White House said Trump was not firing Fauci despite his retweet of a supporter’s #FireFauci message.
At the time, White House spokesman Hogan Gidley said: "Dr. Fauci has been and remains a trusted adviser to President Trump."Aides to Fauci were not immediately available to comment on the House committee's desire to have him testify.