Xi's remarks ahead of an Asia-Pacific Economic Cooperation (APEC) summit in Bangkok were an apparent reference to U.S. efforts with regional allies and partners to blunt what they see as China's growing coercive economic and military influence.
"No attempt to wage a new cold war will ever be allowed by the people or by our times," Xi said in written remarks prepared for a business event linked to the summit.
"We should follow a path of openness and inclusiveness," he said in the speech, which was provided by organizers, adding the region should not turn into "an arena for big power contest."
"Unilateralism and protectionism should be rejected by all; any attempt to politicize and weaponise economic and trade relations should also be rejected by all."
Relations between the world's two largest economies have grown strained in recent years over issues like tariffs, Taiwan, intellectual property, the removal of Hong Kong's autonomy and disputes over the South China Sea, among others.
In a move that may be seen by Beijing as a rebuke, a senior administration official said U.S. Vice President Kamala Harris will on Tuesday visit the Philippine islands of Palawan on the edge of the disputed South China Sea.
The trip will make Harris the highest-ranking U.S. official to visit the island chain adjacent to the Spratly Islands. China has dredged the sea floor to build harbors and airstrips on the Spratlys, parts of which are also claimed by Brunei, Malaysia, the Philippines, Taiwan and Vietnam.
Xi told Philippines counterpart Ferdinand Marcos Jr at a meeting in Bangkok that the strength of bilateral ties hinged on stable relations at sea, China's CCTV state broadcaster said, referring to disputes over areas of the South China Sea.
Harris will visit Palawan after attending the APEC meeting, which follows a series of regional summits so far dominated by geopolitical tension over the war in Ukraine.
At G20 meeting in Bali, countries unanimously adopted a declaration saying most members condemned the Ukraine war, but also acknowledged some countries saw the conflict differently. Host Indonesia said the war was the most contentious issue.
Russia is a member of both G20 and APEC but President Vladimir Putin has stayed away from the summits. First Deputy Prime Minister Andrey Belousov will represent him at APEC.
'Pivotal juncture'
Host Thailand on Thursday said leaders gathering for the APEC forum should "rise above differences".
Its Foreign Minister Don Pramudwinai said the meeting of the 21-member bloc, which starts on Friday, "takes place at a pivotal juncture" with the world facing multiple risks.
"Cancel mentality... permeates every conversation and action, (and) makes any compromise appear impossible," he said in a statement after a meeting of the bloc's foreign ministers ahead of the main summit.
"That's why APEC this year must rise above these challenges and deliver hope to the world at large."
Australian Prime Minister Anthony Albanese is among those also attending the main meeting, while French President Emmanuel Macron is a special guest.