The warning came as Xi Jinping met with US President Donald Trump at his Florida resort in Mar-a-Lago.
The warning came as Xi Jinping met with US President Donald Trump at his Florida resort in Mar-a-Lago, where the Chinese leader had just hours earlier extended an invitation to the billionaire politician to pay a state visit to China later this year, according to the official Xinhua news agency.
China was "concerned" by the recent events in Syria, foreign ministry spokeswoman Hua Chunying told reporters at a regular press briefing, adding: "What is urgent now is to avoid further deterioration of the situation."
"We oppose use of chemical weapons by any country, organisation or individual in any circumstance, for any purpose," she said.
The massive strike -- the first direct US action against President Bashar al-Assad's government and Trump's biggest military decision since taking office -- marked a dramatic escalation in American involvement in Syria's six-year civil war.
Six people were killed and serious damage caused, according to the Syrian army.
News of the air strike overshadowed a two-day tete-a-tete between the Chinese president and his US counterpart, which concludes Friday.
The meeting is the first face-to-face encounter between the leaders of the world's two largest economic and military powers since a US election that featured frequent barbs at China's "rape" of the American economy.
Shortly after his dinner with Xi, Trump announced the strike in a brief televised address delivered hours after the UN Security Council failed to agree on a probe into the suspected chemical attack.
During the meetings, Trump agreed to visit China "with pleasure", saying he hoped to visit at an early date, according to Xinhua, citing officials.
Trump had personally informed the Chinese head of state of the Syrian strike, a White House official told AFP.
China is a veto-wielding permanent member of the UN Security Council, and consistently says the crisis needs a “political solution”.
But it has six times voted alongside Russia to veto UN Security Council measures aimed at addressing the conflict -- including one in 2014 seeking the investigation of war crimes in the country.
Declaring it in America's vital national security interest to prevent the spread of chemical weapons, Trump accused Assad of a "very barbaric attack" in which "even beautiful babies were cruelly murdered."
The attack followed days in which images of dead children and victims suffering convulsions from the suspected sarin gas attack in the rebel-held town of Khan Sheikhun shocked the world.
Syria's regime has denied any use of chemical weapons and state media on Friday described the US strike as an "act of aggression".