After a meeting with Iranian President Muhammad Khatami on Friday, Chavez said both countries rejected the imperialist policies of the United States.
"Iran has every right, like many other countries have done, to develop its atomic energy and continue its research in this field," Chavez said.
The Iranian president is on a visit to Venezuela to strengthen ties between the two countries.
Khatami said both Iran and Venezuela will stand firm against any aggression and lamented "the injustice of the great powers that try to control the world".
"What must be condemned are calls for violence, whether from terrorists or from aggressors with yearnings for domination," Khatami said.
"Iran and Venezuela, these two brothers, are and will be together forever," Chavez said. "Iran, confronted by the United States, has our solidarity."
"Iran has every right, like many other countries have done, to develop its atomic energy and continue its research in this field"
"Like you, we are willing to be free from imperialism," he added.
Chavez presented Khatami with the Order of the Liberator – the country's highest decoration – calling it a symbol of their strong ties.
The meeting came five days before an Organisation of Petroleum Exporting Countries (Opec) summit in Iran where members are to discuss stabilising the oil market amid record-high prices.
Government officials also signed 20 agreements to cooperate in areas including petrochemical projects, economic development, agriculture and the construction of thousands of homes in Venezuela. They also approved millions of dollars in credit lines to boost trade.
Khatami will conclude his three-day visit on Saturday with a trip to open a joint-venture tractor assembly plant that is to bear his name.