In his comments, Castro chided the United States as a "ruined nation" and derided the Tea Party as "extreme right."
Castro also announced that health concerns had forced him to step down from his position as head of the Cuban Communist Party.
Castro's exchange with the students was published in Granma, the state-run newspaper.
"I got sick and did what I had to do -- delegate my powers." Granma reported.
Castro ceded the Presidency of Cuba in 2006 after 46 years in power. He was replaced by his younger brother Raúl.
Under both brothers, Cuba has been isolated from the international community, criticized for its lack of democratic elections and for its systematic abuse of human rights.