Her remarks come as China launched the longest and one of the most controversial torch relays ever on Tuesday amid tight security and great secrecy over the exact route.
Torch relay kicks off
A chartered Air China aircraft left Beijing with the flame heading for Almaty in Kazakhstan, where the first leg of the relay will be run on Wednesday, a Beijing Olympic organising committee official said.
There were no protests in Beijing on Monday as China held an elaborate ceremony to welcome the flame from Greece, but demonstrations are expected during the 137,000km, four months and 19 nations that the relay is to run.
Security has been very tight after anti-government rallies last month in Tibet and the exact route of the relay - set to include an ascent of Mount Everest in the troubled region - will be kept secret to prevent any potential protesters from getting close.
The president of the International Olympic Committee (IOC) is expected in Beijing this week.
And while Jacques Rogge's visit is officially a check on China's preparation for the games, he may meet Chinese leaders to talk about recent events in Tibet.
Pro-Tibet protesters around the world have been demanding that the IOC and world leaders boycott the games.
Namka Tenzin, the president of the Capital Area Tibetan Association, said: "We … urge the president of the United States of America to put pressure on the Chinese government so the problem or the issue of Tibet may be solved."
Modern tradition of torch relay began in 1936 at Berlin Olympics
This year's is the longest ever, travelling 137,000km
The torch will visit 19 nations over 130 days
First destination is Kazakhstan
On the final leg, it will travel throughout China, including Tibet and the summit of Mount Everest
Click here to go to the official torch relay site
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And it is not just Tibet that is causing a headache for the Chinese.
The Chinese government's perceived inaction in Darfur, its relationship with Taiwan, and its human rights record in general are just a few of the issues that are likely to draw organised protests during the relay or the Olympics itself.
Nicolas Sarkozy, the French president, was the first European leader to suggest a boycott of the opening ceremony to protest against China's handling of the unrest in Tibet.
Angela Merkel, the German chancellor, is skipping the Olympics altogether.
The White House has said Bush would not boycott the Olympics because of the crackdown, arguing that the games are supposed to be about the athletes, not politics.
But Pelosi said "the president might want to rethink this later, depending on what other heads of state do".