Speaking on the eve of the celebrations to mark China's 70th anniversary, Xi said that "the complete reunification of the motherland is inevitable" and added that "no one and no force can ever stop it".
"Unity is iron and steel. Unity is a source of strength. It is what has enabled the Chinese people and the Chinese nation to move forward against all risks and challenges, from one victory to another," the President was quoted as saying by Efe news.
Xi's remarks of upholding the territorial unity of the country came as Hong Kong remains plagued by months of pro-democracy protests in the semi-autonomous region that was handed back to China by Britain in 1997.
Hong Kong authorities and pro-democracy activists were gearing up for what was expected to be a highly volatile day amid calls for more demonstration to upstage China's National Day on Tuesday.
In his address, Xi said China "must hold high the banner of unity and rally closely around the CPC Central Committee".
"We must cement the great unity of all our ethnic groups and strengthen the great unity of all Chinese sons and daughters. We must maintain the close bond between the CPC and the people and promote patriotism.
"We will create an unparalleled force that will power the ship of our national renewal to clip waves and reach its destination."
Xi also talked about the big changes faced by the country since its foundation 70 years ago and called it "tremendous transformation" that marked an era.
"The Chinese people, with perseverance and strenuous efforts, have made development achievements that are the marvel of the world," Xi said, pledging that "absolute poverty, which has haunted the Chinese nation for thousands of years, will soon become a thing of the past".
The 70th anniversary of China's foundation will be celebrated on Tuesday with the biggest military parade in the country's history, the report said. More than 100,000 people are expected to participate.
( With inputs from IANS )