State Department spokesperson Ned Price said China could influence Myanmar more than any other country, the BBC reported.
“We are calling on countries around the world to do more. We will be doing more as well,” he said.
Price said there could be “no business as usual” with the junta regime in Myanmar and called on all countries to ban sales of military equipment to the country and “refrain from lending the regime any degree of international credibility”.
He said the US was considering “all options” to cut off the regime’s revenue, BBC reported.
But Zhao Lijian, a Chinese Foreign Ministry spokesman, said Beijing did not interfere in other countries’ internal affairs.
Asked about the executions, Zhao said Myanmar should use its laws and constitution to resolve differences.
Activist Kyaw Min Yu, better known as Ko Jimmy, and former lawmaker Phyo Zeya Thaw were among those executed.
The activists were arrested after an army-led coup last year and accused of committing “terror acts”. They were sentenced to death in a closed-door trial that rights groups criticised as being unjust.
Both Phyo Zeya Thaw and Ko Jimmy lost their appeals against their sentences in June.
Less is known about the two other activists, Hla Myo Aung and Aung Thura Zaw.
They were sentenced to death for killing a woman who was an alleged informer for the junta.