"We do not allow any individual, any organisation, any political party, at any time or by any means to split any single piece of Chinese territory," said Xi, who commands the world's largest standing army.
"No one can expect us to swallow consequences that damage our sovereignty, security, and developmental interests," he said.
On Sunday, addressing the Chinese Army in Inner Mongolia during a parade, Xi said the PLA was capable of defeating invading enemies.
Xi said the PLA had done its duty to counter secessionist forces in Hong Kong and Macau.
The armies of both countries have been engaged in a standoff since June 16 in Sikkim section where India and China share a 220-km-long border.
China has maintained that there won't be a meaningful dialogue without the unconditional withdrawal of Indian troops.
Meanwhile, India maintains that the unilateral action by China to build a road in the area was altering the status quo and had serious security implications for India.
China is locked in a number of territorial disputes - both on waters and land - with various countries. It has, however, settled its land disputes with all 14 but two countries: India and Bhutan.
China claims India's Arunachal Pradesh as its own and calls it South Tibet. India lays claims to Aksai Chin in the western sector, which is under Chinese control.
The decades-old feud between India and China has a new addition: Doklam in the Sikkim section where both armies have been engaged in a stand-off.
Doklam is disputed between China and Bhutan, whose ally India backs Bhutan in its claims over the region. At the tri-junction China, India, and Bhutan, Doklam is of strategic importance to all three.
Beijing wants New Delhi to withdraw troops from Doklam. New Delhi is for a simultaneous pullback of both Indian and Chinese troops.