Xi Jinping, the leader-in-waiting, has denounced Japan's decision to buy disputed islands in the East China Sea as a farce and said Tokyo should "rein in its behaviour" as Beijing moved to snuff out anti-Japan protests.
Relations between Asia's two biggest economies have faltered badly over the disputed islands, known by Japan as the Senkaku and by China as the Diaoyu. Tokyo's nationalist governor, Shintaro Ishihara, floated a plan in April for metropolitan authorities to buy the islets, prompting Japan's government to buy them from their private owner instead in an effort to defuse the crisis.
"Japan should rein in its behaviour and stop any words and acts that undermine China's sovereignty and territorial integrity," Mr Xi said in a meeting with the visiting US Defence Secretary, Leon Panetta, according to Xinhua news agency.
Japanese businesses shut hundreds of stores and factories across China, fearing protests would get out of hand after Japan's Beijing embassy had been laid siege to by protesters throwing water bottles, and chanting slogans.
On Tuesday, about 50 Chinese protesters surrounded and damaged a car carrying the US ambassador, Gary Locke, outside the US embassy.