Machado confirmed her last conversation with Trump occurred on 10 October, the same day her Nobel Peace Prize was announced.
She was awarded the prize for her fight against what the Norwegian Nobel Committee described as a dictatorship.
Widely considered Nicolas Maduro's most credible opponent, Machado travelled to Norway last month to accept the award and has not returned to Venezuela.
Donald Trump recently dismissed the idea of working with Machado, claiming she lacks support and respect within her country.