Sean Penn, the Hollywood star who wants to be a journalist, has now become an amateur diplomat by visiting America’s noisiest enemies in the Southern Hemisphere and promising to relay their messages back to Washington.

After Penn’s visit with Hugo Chavez in Caracas on Wednesday, the Venezuelan strongman said he had discussed politics with Penn, who told him he would soon see President Obama.

“Chavez said he’d asked Penn to tell Obama he should take action to earn his Nobel Peace Prize, and should scrap a plan for the US military to increase its presence at bases in Colombia,” the Associated Press reported on their session.

“They gave him the Nobel Prize — very well, now he should earn it,” admonished the socialist Chavez, paraphrasing his friend, documentary filmmaker Michael Moore.

Penn had come from Cuba, where he reportedly tried to meet with his other hero, Fidel Castro, 83, who hasn’t given an interview to a Western journalist since he was felled by intestinal illness three years ago.

The Oscar winner’s publicist, Mara Buxbaum, didn’t know about Penn’s visits with either Castro or Obama. State Department spokesman Noel Clay told Page Six, “Sean Penn is a private person. He’s entitled to his views and opinions. He doesn’t speak for the US government.”

This was Penn’s third visit with Chavez. Last year, he interviewed Castro’s younger brother, Raul, for a meandering, star-struck piece in The Nation in which Penn gushed: “There is humor in Raul’s face that recalls a lifetime of affectionate tolerance for his big brother’s watchful eye.”

Celebrity-magnet Chavez, who’s already been glorified in an Oliver Stone documentary, has also met with Naomi Campbell, Danny Glover, Benicio Del Toro and Courtney Love.