Asked about the Trump administration's possible move to exit from the Paris climate agreement, Li said China would uphold its commitments.
Experts say that while the USA move is expected to have profound implications for the worldwide effort tackling climate change and would deal a major blow to Washington's global standing, it has presented China with an unprecedented opportunity to emerge as a global leader on climate issues.
Trump is expected to say whether to keep the United States in a global pact to fight climate change, and a source close to the matter told Reuters said he was preparing to pull out of the Paris accord.
Tapping into the "America First" message he used on the election trail, Trump announced the withdrawal Thursday.
Xie Zhenhua, China's special representative on climate change, said in January, just days before Trump was sworn in as the new U.S. president, that China was already "capable of taking a leadership role" in the global campaign against climate change.
The flurry of visits come as concern grows in traditionally Atlanticist Germany at Trump's forthcoming announcement on the Paris Climate Accord, created to reduce the carbon dioxide emissions scientists blame for rising sea levels and droughts. "We continue to lobby the U.S. at all levels to continue to take climate change extremely seriously".
"We will continue to lobby the Americans and the White House to show the leadership they have shown in the past on reducing CO2", he said.
While travelling overseas last week, Mr Trump was repeatedly pressed to stay in the deal by European leaders as well as Pope Francis. The other two are Syria and Nicaragua.
Russian Federation joined the chorus speaking out in favour of the climate accord. But Elliot Diringer, the executive vice president of the Center for Climate and Energy Solutions, a nonpartisan climate-focused think tank, said he was confident most would remain committed to climate action.
During a trip to Europe this week, Indian Prime Minister Narendra Modi expressed India's commitment to fighting climate change and said it would be a "crime" to spoil the environment for future generations.
"Those who want to export their goods and services to our market also have to accept our standards", he said.