Chavez met privately with Penn for two hours Thursday, praising the actor as "brave" for urging Americans to impeach President Bush.
"In the name of the peoples of the world, President Bush, withdraw the troops from Iraq. Enough already with so much genocide," Chavez said before an auditorium packed with his red-clad supporters.
Chavez said he and Penn discussed the question of "why the (U.S.) empire attacks Chavez so much," saying Venezuela's oil wealth is a key reason.
He also said Washington is "afraid that the people of the United States will learn the real truth" about the situation in Venezuela, citing his social programs for the poor.
"If the people of the United States, those millions and millions of poor people ... if that nation realizes what is truly happening here, there would be a revolution in the United States," Chavez said, eliciting applause from Penn.
Some Chavez opponents were angered by Penn's visit.
Cuban-born actress Maria Conchita Alonso, who grew up in Venezuela, said Penn is lending support to a "totalitarian" leader who wants increasing control of society — a charge Chavez denies.
In a phone interview from her home in Beverly Hills, California, Alonso said although she respects Penn as an actor, she hopes he "comes to his senses and he realizes that he's being used."
Penn did not speak publicly. Chavez said the actor came wanting to learn about Venezuela.
"That man has opposed the war in Iraq with all his strength, and not only that, he went to Baghdad ... and now he comes here. He's going around touring the 'axis of evil,"' Chavez said with a chuckle.