In a lengthy letter, the 89-year-old former Cuban leader said his country "has no need of gifts from the (US) empire." The scathing note follows a landmark visit by Obama amid a warming of ties.
Castro Senior's letter, entitled "El Hermano Obama" (Brother Obama), contains his first published remarks since Obama's three-day visit to Havana last week, during which the former Cuban president remained out of sight.
His 1,500 word note appeared to ignore a strengthening of relations between the two former foes by declaring that Cuba "has no need of gifts from the empire."
"Listening to the words of the US president could give anyone a heart attack," Castro said, in another barbed comment, referring to Obama's speech.
"Nobody has any illusion that the people of this noble and selfless country will surrender glory and rights and the spiritual wealth that has come through the development of education, science and culture," he added, inthe note which was published in the Granma newspaper.
"My modest suggestion is that he (Obama) reflects and doesn't try to develop theories about Cuban politics," he added.
Spoke in the wheel?
Last week, Obama said he had come to bury the two countries' history of Cold War hostility but questioned Cuba's human rights record and called for democracy and greater freedoms. His visit was the first by a US president in 88 years.
Although he did not meet with Fidel Castro, he did hold talks with his brother Raul Castro, the current president, who has proven to be far more reform-minded.
Over the past year, the US and Cuba have restored formal diplomatic relations, Washington has reopened its embassy in Havana, and travel restrictions have been eased on Americans traveling to Cuba.
A US embargo against Cuba still remains in place. During his visit, Obama reaffirmed his desire for the US Congress to scrap the trade restrictions.