The chairman of the US Senate’s Health Committee, Lamar Alexander, warned that this could hinder preventive care.
Mr Alexander, a Republican, said Trump’s move could prevent international cooperation in preventing the spread of the virus in the United States.
The European Union demands that Trump change his mind. Germany says the president’s step is the world’s worst decision made.
President Trump has insisted that China has dominated the World Health Organization, and the agency has failed to provide the needed changes.