Calls by US President George W Bush for Cubans to work for democratic change have been dismissed as "the epitome of delirium" by Cuban state-run TV.
Life goes on as normal, but rumours abound
Commentators were reacting to Mr Bush's first public statements on the issue since Monday's announcement that Fidel Castro had undergone stomach surgery.
President Castro, 79, has temporarily ceded power to his brother, Raul.
Despite official statements that Fidel Castro is recovering, rumours about his health abound, both in Cuba and the US.
While life goes on as normal on the island, correspondents say Raul Castro's failure to appear in public and a lack of information about his brother's whereabouts are fuelling speculation about the future.
In Miami - where there is a large Cuban exile community - many have been celebrating what they believe to be Fidel Castro's demise.
Those celebrating were described as "vampires" by Cuban TV commentators.
On the nightly news discussion programme, commentators also dismissed any US plan for change in Cuba.
"The only way to apply the Bush plan for regime change in Cuba is by force, and force will not work," Communist Youth newspaper editor Rogelio Polanco said.
"Raul is firmly at the helm of the nation and leading the armed forces that have a proven combat record and international experience. Make no mistake," he said.
Mr Bush has pledged Washington's support for Cubans who seek to "build a transitional government in Cuba committed to democracy".
A US imposed an embargo on the Caribbean island in 1962 - three years after Mr Castro took power - which remains in place.
Fidel Castro - who turns 80 this month - is one of the world's longest-ruling leaders, and has outlasted nine US presidents.