CARACAS, Venezuela — Venezuelan President Hugo Chavez defended his decision not to renew the license of a popular opposition-aligned television network and warned Tuesday he might crack down on another TV station, accusing it of trying to incite attempts on his life.

Chavez said his refusal to renew the license of Radio Caracas Television, which went off the air at midnight Sunday, is "a sovereign, legitimate decision."

He said another station Globovision — one of the few channels that is still harshly anti-government — had encouraged attempts on his life and could also face sanctions.

"I recommend (Globovision) take a tranquilizer, that they slow down, because if not, I'm going to slow them down," Chavez said in a speech.

Chavez did not elaborate, but said some broadcasters and newspapers are conspiring to spark unrest and warned that radio stations should not be inciting violence by "manipulating" public sentiment.

"A new destabilization plan is under way," Chavez said, calling for his supporters to be "on alert" and ordering officials to closely monitor media coverage.

Globovision's legal adviser Perla Jaimes told The Associated Press that Chavez had no legal basis to sanction the channel and said it would not be intimidated by the warnings.

"Globovision is not going to change its editorial line," Jaimes said. "We cannot stop transmitting the news. We cannot self-censor. We have to broadcast everything that is happening in the country."

Thousands — both Chavez supporters and opponents — staged separate marches in Caracas on Tuesday. The Chavez opponents chanted "freedom!" while government supporters said they were in the streets to reject an opposition attempt to stir up violence.

Information Minister Willian Lara on Monday accused Globovision of encouraging an attempt on Chavez's life by broadcasting the chorus of a salsa tune — "Have faith, this doesn't end here" — along with footage of the 1981 assassination attempt against Pope John Paul II.

Globovision director Alberto Federico Ravell denied wrongdoing, calling the allegations "ridiculous." Globovision replayed footage of the assassination attempt during a retrospective of news events covered by RCTV during its 53 years on the air.

The government turned over RCTV's license to a new state-funded public channel, which showed a documentary on explorers in Antarctica, a children's program and exercise programs, interspersed with government ads repeating the slogan "Venezuela now belongs to everyone."

Chavez says it is a move to democratize the airwaves. He accused RCTV of helping incite a failed coup in 2002, violating broadcast laws and "poisoning" Venezuelans with programming that promoted capitalism.

While Chavez made his speech Tuesday, thousands of students and opposition supporters marched to the offices of the Organization of American States, where they urged the body to take a stand chanting, "This is a dictatorship!"