A Reuters journalist later saw Guido near the Karlotta Air Force base in Caracas, surrounded by a group of men in uniform.
"The government faces a small group of military traitors" who seek to encourage the coup, Venezuelan Information Minister Jorge Rodriguez said on Twitter.
Guido spoke in a video posted on his Twitter account with men in military uniform and politician Leopoldo Lopez.
Lopez claimed that the army liberated him and called on all Venezuelans to go to the streets peacefully.
Lopez was under house arrest for his anti-government campaign in 2014.
"The national armed forces have made the right decision and rely on the support of the Venezuelan people," Guido said.
Guido is planning the protests on Wednesday (May 1st) and will be "the biggest march in the history of Venezuela," Guido said, part of what he calls the "final stage" of his efforts to take office to call for new elections.