He also predicted that the world would eventually revolt against US hegemony in international affairs.
Chavez said all Latin American revolutions must clash with Washington and accused US officials of conspiring to cause political upheaval in Venezuela ahead of presidential elections in December.
"Sooner of later, we, the people, the nations, will break this scheme imposed in the United Nations so there are truly free and united countries, not the dictatorship there in the United Nations against the nations and people of the world," he said.
Chavez has rejected allegations by the US that he has become a destabilising force in Latin America.
He says that movements such as his so-called Bolivarian Revolution in Venezuela must take root by themselves.
During his speech to newly appointed ambassadors on Tuesday, Chavez said he believes that every Latin American revolution must be opposed to US interests.
"Whoever tries to push a transformation project forward in Latin America inevitably will collide with the US empire," said Chavez, a close ally of Fidel Castro, the Cuban leader.
"I think the collision is necessary."
He applauded steps that Evo Morales, the Bolivian president, has taken toward nationalising the Andean nation's natural gas reserves.
Chavez urged Venezuelans to think of Latin America as the single nation that 19th-century independence hero Simon Bolivar dreamed of establishing centuries ago.
"That country is part of our nation because we are truly one single nation, it's part of our fatherland because we are a single fatherland," Chavez said.
"We are with Bolivia, fatherland or death!"
US officials, who see Chavez as a threat to stability in Latin America, have expressed hope that Morales will not emulate the Venezuelan leader.