Ukrainian President Viktor Yanukovych met last weekend with opposition leaders in a bid to end a political standoff that erupted with the president's decision in November to suspend efforts to sign trade agreements with the European Union.
Pro-EU demonstrations turned violent in January when the Yanukovych administration backed legislation restricting protests. During the weekend, the president offered opposition leader Arseniy Yatseniuk the job of prime minister to quiet the protests.
Rasmussen said Monday from Brussels he was concerned by the way events in Ukraine were unfolding.
"I urge all parties to prevent further escalation and violence and work for a solution based on dialogue," he was quoted by the National News Agency of Ukraine as saying.
The Ukrainian government threatened to impose a state of emergency after protesters occupied some government buildings.
Ukraine is not a member of NATO. The Yanukovych administration said the EU decision in November was made to protect Ukraine's economic ties to Russia.