Machado, who has been in hiding due to persistent threats, was smuggled out of Venezuela with US military assistance to attend the Nobel ceremony in Oslo.
Trump had previously commented that it would be "tough" for Machado to lead Venezuela, despite her being considered a frontrunner after Nicolas Maduro's capture.
Machado has publicly dedicated her Nobel Peace Prize to Trump, expressing her belief that he deserved it for his actions against Maduro.
Sources close to the White House suggested Trump's negative remarks were prompted by Machado accepting the prize, which was reportedly seen as an "ultimate sin" by him.