UN Secretary-General Kofi Annan has urged Chinese and Japanese leaders to use this week's Asia-Africa summit in Indonesia to improve their relations.
The Chinese government seems to approve of the protests
Mr Annan said China and Japan had important ties and he hoped they could resolve their differences peacefully.
The two countries blame each other for a row which has led to violent anti-Japanese demonstrations in China.
Chinese protesters are angry about new Japanese school textbooks, which they say gloss over wartime atrocities.
'Harsh words' fear
The Asia-Africa summit is expected to be attended by the Chinese President, Hu Jintao, and Japan's Prime Minister, Junichiro Koizumi.
Japan's Foreign Minister Machimura Nobutaka finished a fence-mending visit to China on Tuesday without resolving the crisis.
China's State Councillor Tang Jiaxuan told Mr Nobutaka that Japan had "repeatedly failed the trust of the Chinese people," and damaged ties between the two nations, state media reports.
Mr Machimura had asked for apology and compensation from China for its failure to stop demonstrators from damaging the Japanese embassy in Beijing, consulate generals and Japanese enterprises.
But China says it has nothing to apologise for.
Mr Annan said Prime Minister Koizumi and President Hu should meet at the Asia-Africa summit which opens on Thursday.
"They have lots of relationship on all fronts - political, economic and social - and I hope those important aspects of their relationship will encourage them to resolve their differences," he said.
The Chinese foreign ministry said it was still considering the meeting, which Japan has proposed as well.
But Mr Koizumi said: "If it's going to be the exchange of harsh words, it's better not to meet".
Japanese officials are increasingly concerned about long-term damage to booming trade and investment between the two countries.
Saturday and Sunday saw the third consecutive weekend of anti-Japanese protests in China. There were large demonstrations, involving thousands of people, in Shenzhen and Shanghai, and smaller protests reported in the cities of Shenyang, Zhuhai, Dongguan and south-western Chengdu.
Analysts say the scale of the disturbances is unusual for China, and indicates tacit official support for the protesters.
But our correspondent says Beijing appears to be moving towards controlling activities in certain areas - for example, university students have been told to stay on campus.
The protests were triggered by Japan's decision to approve eight school textbooks which critics say gloss over the country's actions before and during World War II.
Among the issues causing outrage is the description of the Japanese army's massacre of between 50,000 and 300,000 civilians in the Chinese city of Nanjing in 1937 and 1938 as "an incident".
Tokyo says private companies, not the government, were responsible for the texts, and that it is up to individual school districts to decide which books they use.