Sirhan is "very hostile. He hates Americans. ... He continues to pose a risk to public safety," said state Board of Parole Hearings spokesman Tip Kindel.
Sirhan did not attend the hearing at Corcoran State Prison or appoint a lawyer to represent him. His longtime attorney died last year after numerous failed attempts to get his client a new trial.
Sirhan also did not appear at his last hearing in 2003. Periodical hearings are guaranteed by law. Sirhan's next parole hearing will be in 2011.
Kennedy was shot in the narrow pantry of Los Angeles' Ambassador Hotel on June 5, 1968, soon after the New York senator claimed victory in the California presidential primary.
Sirhan was wrestled to the ground with the gun in his hand.
Prosecutors at Sirhan's trial said the Palestinian immigrant targeted Kennedy because of his pledge to sell fighter jets to Israel.
Sirhan blurted out in court that he killed the senator "premeditatedly with 20 years of malice aforethought," but later insisted he did not remember the incident.