In Bolivia's capital of La Paz, Morales said, "We do not want people here who conspire against democracy," The New York Times reported Thursday.
Morales, a leftist and ally of Venezuelan President Hugo Chavez, contended Goldberg was helping groups seeking greater political autonomy in eastern Bolivia.
Officials at the U.S. Embassy in Bolivia, who have denied the accusations, told the Times late Wednesday the mission had received no official notification of the expulsion and Goldberg was performing his duties.
"We are therefore trying to establish the intent of the president's remarks," said U.S. State Department spokesman Edgar Vasquez, who called Morales's charges "baseless."
Goldberg's expulsion Wednesday came hours after Bolivian officials blamed anti-government protesters for disrupting gas exports to Argentina and Brazil, The Wall Street Journal reported.