"China demands the parties to the conflict stop the firing immediately, take all measures to prevent further escalation of the situation... and prevent incidents that sabotage the peace and stability in the China-Myanmar border region," Chinese Foreign Ministry spokesperson Lu Kang told reporters during a daily press briefing Monday.
Several rockets and stray bullets fell on Chinese territory and more than 300 refugees fled to China after the deadliest flare-up of violence in the area in recent years, said Lu.
"China is highly concerned about the armed conflicts that took place in northern Myanmar on May 12," Lu said.
"According to what we have learned, as of now, the conflict has caused the death of two Chinese nationals in Myanmar, and three rockets and some stray bullets have fallen into Chinese territory."
China has also offered temporary shelter to "more than 300 Myanmar border residents who entered China to flee the violence," Lu said.
The Ta'ang National Liberation Army, one of several insurgent groups fighting for more autonomy in the north, said it launched the operation on Saturday.
Saturday's attack was launched outside the town of Muse in Shan state, which is situated at a major border crossing and trading post between Myanmar and China's Yunnan Province.