Foreign Minister Ali Rodriguez on Wednesday dismissed as "impertinent" charges Venezuela limits free speech.
He also ruled out accusations that Caracas associates with Colombian guerrillas and is a destabilising force in the region.
"The absurdity of these accusations against our government would not cause us the least anxiety if it were not for so many facts demonstrating that these signs appear because, sooner or later, there will be an attack," Rodriguez said.
Addressing the Organisation of American States in Washington, the minister said the history of Latin America, where the US is notorious for seeking decades ago to undermine leftist governments, showed such rhetoric was a way of preparing the ground for more drastic moves against Venezuela.
Rodriguez, however, did not elaborate what sort of attack he was referring to, but he repeated Chavez's assertion that the Bush administration was behind a plot to assassinate him.
Washington brushed aside Rodriguez's claims.
Political analysts said Rodriguez's appearance at the headquarters of the top diplomatic body was part of Venezuela's counteroffensive to win over Latin American governments in its spat with the US.
"The absurdity of these accusations against our government would not cause us the least anxiety if it were not for so many facts demonstrating that these signs appear because, sooner or later, there will be an attack"
Venezuelan foreign minister
Chavez has angered Washington by his friendship with Cuban President Fidel Castro, hawkish oil price policies in Opec and fierce opposition to US free trade moves in the region.
But political analysts say US options against Chavez are limited because he has won a clear mandate from his electorate, has generally friendly ties with governments in the region, and is buoyed by high oil prices.
Larry Birns of the Washington-based thinktank, the Council on Hemisphere Affairs, said Venezuelan worries over a possible attempt on Chavez should not be dismissed as paranoia.
"Chavez's rhetoric can be disregarded as bark without bite but when the Bush administration is barking so much you can understand the Venezuelans would be concerned it may actually be ready to bite," Birns said.