Simonyte was commenting on the EU's stalled talks on a fresh round of sanctions against Moscow and on a suggestion by Henry Kissinger, a former US secretary of state, that Ukraine should cede part of its territory to make peace with Russia.
"If the West steps on the same rake again, that rake will smack it in the face again and that will definitely not be the end of this story," she said in an interview with the Delfi online news site on Wednesday.
The prime minister noted that some politicians believe that the situation in Ukraine can be resolved outside the battlefield.
"These things are worrying, but I see this, at least for now, as wishful thinking on the part of individual European politicians," she said.
The EU is currently discussing the sixth package of sanctions against Russia for its invasion of Ukraine.
The new package includes a ban on Russian oil imports, but the talks are stalling due to opposition from Hungary, which is heavily dependent on Russian energy resources.