In comments reported by state television and newspapers on Wednesday, Foreign Minister Li Zhaoxing appealed for calm and said the public should avoid taking part in unauthorised protests.
"Do not participate in unapproved marches and other activities and do not do anything that will affect social stability," Li was quoted as saying. "Express yourselves calmly, rationally and in an orderly fashion."
Li's appeal repeated official demands for calm, issued since last week in government statements and by state newspapers.
But it was the first time a member of the Chinese leadership has made the appeal in public, and Li's comments on Tuesday were more widely publicised, appearing on state television and the front pages of some newspapers on Wednesday.
Li gave no indication that China might apologise for letting rioters damage the Japanese embassy and a consulate in protests over the Security Council seat, and complaints that new Japanese textbooks downplay wartime atrocities.
"Turn your patriotic passion into pragmatic activities such as jobs and diligent studying. Contribute yourself to the prosperity of the Chinese nation," Li said.
"Turn your patriotic passion into pragmatic activities such as jobs and diligent studying. Contribute yourself to the prosperity of the Chinese nation"
Chinese foreign minister
He said improved relations between the two sides hinged on Japan taking a "correct view of history".
Japan's attitude towards its history had "deeply hurt the national feeling of the Chinese people and brought complexity to Sino-Japanese relations", Li said.
Despite the appeals, anti-Japanese activists have issued a circular and posted calls on websites for more protests on the 1 May Labour Day holiday and on 4 May - the anniversary of a 1919 student uprising over a treaty that ceded part of China to Japan.
Chinese President Hu Jintao headed to Southeast Asia on Wednesday and a possible meeting with Japanese Prime Minister Junichiro Koizumi, to try to ease tensions.
Japanese Foreign Minister Nobutaka Machimura, on a crisis mission to Beijing earlier this week, proposed a meeting on the sidelines of the Asia-Africa summit in Jakarta, but China has yet to respond affirmatively.
"The Chinese side is researching it," Chinese Foreign Ministry spokesman Qin Gang said on Tuesday.
Some analysts, however, are betting the two leaders will meet on Friday.