The attack on Castaņeda in the Communist Party daily Granma was the most serious incident in recent sparring between the two nations' foreign ministries.
Although it called Castaņeda the ''diabolical and cynical architect'' of Castro's decision to leave the forum, Granma insisted that Cuba wants good relations with Mexico ``and not harm in the least the authority and prestige of President Fox.''
''We ask for nothing more than an end to the provocations, insults, lies and macabre plans of Mr. Castaņeda against Cuba,'' the newspaper said in an editorial. ``Otherwise, there remains no other alternative than to divulge that which we have not wanted to divulge, making dust of his false and cynical pronouncements.
''Cuba has irrefutable proof of all that occurred,'' it added.
After Castro suddenly left the forum in Monterrey on Thursday, Cuban officials claimed that Mexico bowed to pressure from the United States to ensure that Castro did not attend the meetings of heads of state being held in conjunction with the U.N. gathering.
Both countries denied those charges.
Cuba didn't single out Castaņeda for attack until Tuesday.
In Mexico City, meanwhile, some Mexican lawmakers are demanding an explanation from Castaņeda, and others want him fired over the incident with Castro.
Politicians from the far left of Mexico's political spectrum accused Castaņeda on Monday of turning his back on Mexico's foreign policy in order to placate President Bush, who made it clear he did not want to cross paths with Castro at the U.N. meeting.
''Precisely because of one person, the relations that Mexico and Cuba have enjoyed for many years are in danger,'' said Congressman Sergio Acosta Salazar, of the leftist Democratic Revolution Party.
Several opposition politicians, including members of the former ruling Institutional Revolutionary Party, said they would ask Castaņeda to appear before Congress as soon as next week to explain his actions