The People's Daily editorial comes as Beijing ramps up efforts to assert its stance ahead of a ruling by an international tribunal in a case filed by the Philippines challenging China's claims to most of the South China Sea.
China is boycotting the case before The Hague-based court and says it will not accept the verdict.
The paper said that bilateral ties and regional stability were at stake and that the US should recognise that "there is a bottom line with every issue, and a price will be paid if that line is crossed."
"China has a solid-rock position over safeguarding China's national sovereignty and territorial integrity. It will not want anything that does not belong to it, but it will ensure that every inch of land it owns is safe and sound," the paper wrote.
The newspaper has previously accused Washington of seeking to turn the South China Sea "into a powder keg" and warned it not to underestimate China's determination to defend its territorial claims.