Speaking at an annual summit involving members of the Association of Southeast Asian Nations (ASEAN) and China, Japan and South Korea, Li said countries needed to "appropriately handle differences and disputes".
"At present, it is very important to oppose taking sides, bloc confrontation and a new Cold War," Li told the meeting.
ASEAN, which has warned of the danger of getting dragged into major powers' disputes, is also holding wider talks with Li, US Vice President Kamala Harris, and leaders of various partner countries including Japan, South Korea, Australia, and India.
Neither US President Joe Biden nor his Chinese counterpart, Xi Jinping, is attending the summit.
High on the agenda at the gatherings in Jakarta, is concern about China's increasingly assertive activity in the South China Sea, an important trade corridor in which several ASEAN members have claims that conflict with China's.
ASEAN this week discussed with China accelerating negotiations on a long-discussed code of conduct for the waterway, said Foreign Minister Retno Marsudi of the ASEAN chair, Indonesia.
The issue also came up during an ASEAN-Japan summit where leaders "expressed the importance of keeping situations in the region conducive, especially in the Korean Peninsula and also the South China Sea", she said.
The United States and its allies have echoed ASEAN's calls for freedom of navigation and overflight and to refrain from building a physical presence in disputed waters. China has built various facilities, including runways, on tiny outcrops in the sea.
"The vice president will underscore the United States' and ASEAN's shared interest in upholding the rules-based international order, including in the South China Sea, in the face of China's unlawful maritime claims and provocative actions," a White House official said on Tuesday.
Just before this week's gatherings, China released a map with a "10-dash line" showing what appeared to be an expansion of the area it considers its territory in the South China Sea.
Several ASEAN members rejected the map.
Referring to the South China Sea, the president of the Philippines, Ferdinand Marcos, said his country did not seek conflict but had a duty to "meet any challenge to our sovereignty".
"The Philippines firmly rejects misleading narratives that frame the disputes in the South China Sea solely through the lens of strategic competition between two powerful countries," Marcos said.
"This not only denies us our independence and our agency, but it also disregards our own legitimate interests."
The summit also saw South Korean President Yoon Suk Yeol pledge to work with Japan and China for the early resumption of a three-way talks between them in building better ties.
Yoon said any military co-operation with North Korea must stop. The New York Times reported on Monday that North Korean leader Kim Jong Un plans to travel to Russia this month to meet President Vladimir Putin and discuss supplying Moscow with weapons for the war in Ukraine.
The 10 members of ASEAN held their summit earlier in the week with leaders seeking to assert the bloc's relevance in the face of criticism it is failing to press Myanmar's military leaders to co-operate on a plan for peace in their strife-torn country.
