It would be "a great pity" if such action took place, Ms Jowell said.
Aspects of Chinese policy were seen as "wholly unacceptable", she continued, but the Games had been awarded to China nevertheless.
Ms Jowell told The Times: "The world has known for the last seven years that Beijing would host the Olympics.
"Most progressive governments accept that there are wholly unacceptable aspects of Chinese policy but that did not stop the International Olympics Committee (IOC) awarding them the Games.
"A call for a boycott doesn't serve any purpose and it would be a great pity.
"This doesn't mean, however, we should we distracted from the urgency of Darfur."
More than 200,000 people have been killed and a further 2.5 million forced from their homes in the five-year conflict between Sudan's Arab-dominated government and Darfur's ethnic African rebels.
Human rights activists have accused China of being partly responsible for Darfur's chaos because of its staunch diplomatic backing of the Sudanese government.
But China said today that "ulterior" motives were behind some criticism of its actions in Sudan, and that the problems there should not be linked with this summer's Olympics.
Foreign Ministry spokesman Liu Jianchao said: "It is understandable if some people do not understand the Chinese government policy on Darfur, but I am afraid that some people may have ulterior motives, and this we cannot accept."
Meanwhile, eight Nobel laureates are among the signatories of a letter to Chinese President Hu Jintao calling for urgent action on Darfur.
The letter, signed by Nobel peace laureates, Olympic athletes, government officials and business leaders, outlines that, as host of the 2008 Olympic Games, China has a "special role to play in the Olympic ideals of peace and international co-operation".
According to the letter's signatories, China has doubled its trade with Sudan in 2007, "providing resources that make it easier for that government to continue to carry out its atrocities".
Published in The Independent, the letter states: "The atrocities in Darfur continue to intensify. Of the seven million inhabitants of Darfur, hundreds of thousands have already died due to the conflict and 2.5 million have been displaced. Rape and sexual violence have been and continue to be used as weapons of war against untold numbers of girls and women."
The Nobel peace laureates who have signed the letter are Bishop Carlos Filipe, Dr Shirin Ebadi, Adolfo Perez Esquivel, Rigoberta Menchu, Archbishop Desmond Tutu, Professor Elie Wiesel, Betty Williams and Professor Jody Williams.
The letter adds: "As the 2008 Beijing Olympic Games approach, we will continue to call on the Chinese government for action. We are aware of the tremendous potential for China to help bring an end to the conflict in Darfur.
"We will continue to watch for concerted and consistent Chinese action to ensure rapid deployment of UN-AU peacekeepers, progress in the peace talks, and an end to the use of rape as a weapon of war."
Several high profile personalities have spoken out, including US film director Steven Spielberg, who withdrew from his role as an artistic adviser to the Games in Beijing over China's lack of progress in resolving the humanitarian crisis in Darfur.
Spielberg, in a statement released to trade magazine Variety, said: "I find that my conscience will not allow me to continue with business as usual.
"At this point, my time and energy must be spent not on Olympic ceremonies but doing all I can to help bring an end to the unspeakable crimes against humanity that continue to be committed in Darfur."
Actress Uma Thurman, whose father is one of the world's leading Tibetan Buddhist scholars, also called for further protest against China's "appalling" human rights record in Tibet.
She said: "Although there is so much good in China and in the Chinese people, the human rights record of the Chinese government is appalling."
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