Hundreds of police traveled in trucks along the main road through the mountains into southeastern Tibet. Others patrolled in riot gear and helmets in the area above the tourist attraction Tiger Leaping Gorge, reported the Associated Press.
Government officials acknowledged for the first time that protests against Chinese rule of Tibet have spread to Tibetan communities in other provinces after sweeping through the ancient Tibetan capital of Lhasa last week.
Also, police opened fire and wounded four protesters earlier this week in unrest in a Tibetan town. Citing police sources, the state-run Xinhua news agency reported Thursday that Chinese police opened fire and wounded four protesters on Sunday in Aba county, an ethnic Tibetan part of the western province of Sichuan.
The police said they acted in self-defense, but it marks the government's first admission that security forces used lethal force to crack down on demonstrations.
Protests started peacefully in Lhasa early last week but turned violent on Friday. Authorities say 325 people have been injured and 16 people have died, according to the AP.
China said the Dalai Lama -- the leader of Tibet's exiles who is currently in Dharmsala, India -- planned the protests, but he said he is not seeking independence for Tibet.
The Dalai Lama offered to meet with Chinese President Hu Jintao and other Chinese leaders, though he said he would not travel to Beijing unless there was a "real concrete development," quoted the AP.
Chinese Foreign Ministry spokesman Qin Gang said the government suggests foreign tourists stay out of western Gansu and Sichuan provinces, the scene of earlier clashes between protesters and police.
Pro-Tibetan independence groups have called on the international community to boycott the August opening ceremony of the Olympic Games in Beijing.
White House spokeswoman Dana Perino said there was no change in President Bush's plans to attend the ceremony and that the spotlight on Beijing could be a good thing, Reuters reported.
"That way the Chinese can hear how people feel and then maybe have an opportunity to either explain their position or maybe even change the things that they are doing," she said.
The Olympic torch relay starts next week, crossing 19 countries and passing through Tibet.