"I wouldn't say they're on the brink of civil war," Xinhua quoted State Department spokesperson Marie Harf as saying at a news briefing.
Russian President Vladimir Putin told German Chancellor Angela Merkel over the phone Wednesday that Ukraine was "on the verge of civil war" as the government had launched military operations to flush out pro-Russian militants who were occupying government buildings in the eastern part of the country.
"Any destabilisation that's going on inside Ukraine right now is a direct result of Russian action there," Harf said, adding "it's ironic to me that they seem concerned about the stability of Ukraine when they're the ones trying to destabilise massive parts of it."
Russia has warned Ukraine against using force to restore order in the country's east, saying the step would end future cooperation and scuttle a four-party meeting slated for Thursday in Geneva between the EU, the US, Russia and Ukraine.
The Kiev government was continuing its campaign, with some Ukrainian troops having reportedly defected to the militants' side.