Qi Zhala, secretary for the Lhasa Communist Party, called for tightened security near Tibetan monasteries after clashes last week turned deadly.
"We must strike hard at all the separatist, destructive and criminal activities of the Dalai (Lama) clique and make efforts to realize our goal of not letting any incident, big or small, occur," he was quoted by the BBC as saying.
Self-immolations are on the rise in parts of central China. More than a dozen such acts have been reported by Tibetan activist groups in the last year. Free Tibet, a rights group in London, said many people are protesting Chinese security measures and the lack of religious freedom.
Tibetan rights groups said the death toll attributed to Chinese forces is much higher than Beijing estimates. The Chinese government, however, claims Western media are distorting the security situation in Sichuan province.
Tibetan activists are calling for more autonomy and the return of spiritual leader, the Dalai Lama.