Xinhua said Xi "has ordered to send a special envoy to Kuala Lumpur". It did not name the envoy.
In a separate statement, Chinese Premier Li Keqiang said China will ask Malaysia to provide more detailed and accurate information on the plane, according to a government microblog account.
Li said the most important task at present is to search for the missing plane and he expressed sympathy to the family members.
Earlier, China's Foreign Ministry said it hopes Britain will provide satellite data by British firm Inmarsat on the missing Malaysian Airlines plane.
When asked whether China wants Britain to give China the satellite information, Foreign Ministry spokesman Hong Lei said he hoped the "relevant country" could provide it.
Citing groundbreaking satellite-data analysis by Inmarsat, Malaysian Prime Minister Najib Razak said on Monday that Malaysia Airlines Flight MH370, which vanished more than two weeks ago while flying to Beijing from Kuala Lumpur, had crashed in the southern Indian Ocean.
Meanwhile, dozens of angry relatives of passengers on the missing Malaysia Airlines jetliner clashed with police outside the Malaysian Embassy in Beijing on Tuesday as they demanded the airline and the government in Kuala Lumpur explain what happened.
The relatives threw water bottles at police, who had formed a human wall around the embassy gate. Many of the protesters were pushed back, witnesses said. A woman who fainted was carried away on a stretcher. REUTERS