"We are the axis of evil," Castro joked, using the label some officials in Washington have used in the past for the leftist alliance Castro and Chavez have built to oppose US policies in Latin America.
Castro handed power over to his brother, Raul Castro, on July 31 last year before undergoing emergency intestinal surgery.
He has not appeared in public since, although he has been seen in video footage.
Castro, 81, appeared frail in a 17-minute video taped during a four-hour meeting with Chavez on Saturday and shown before his phone call on the Chavez broadcast.
The broadcast from the Che Guevara mausoleum in the Cuban city of Santa Clara was a tribute to the revolutionary icon who was captured and executed by Bolivian soldiers 40 years ago.