"I am deeply worried by the Ukrainian parliament's adoption of draft laws that could limit the basic freedoms of citizens, impede on freedom of assembly and speech and curtail the activities of non-governmental organization," he said in a statement.
Members of the Verkhovna Rada, the Ukrainian parliament, passed a handful of measures Thursday that would restrict the right to protest.
Schulz said the measures could turn Ukraine, a former Soviet republic, into an authoritarian state if passed.
"I call on President [Vicktor] Yanukovych not to sign the draft laws and ensure that any legal changes are compatible with Ukraine's international commitments," he said.
Demonstrations erupted in November when the Yanukovych administration decided to suspend efforts to sign free trade and association agreements with the European Union. The president said the decision was made to protect economic ties with Russia.
Jen Psaki, a spokeswoman for the U.S. State Department, said in a Thursday statement if Ukraine still wants to join the EU, it should defend, not undermine, democratic principles.
"We need to see a clear commitment from the Ukrainian authorities that they are serious and sincere about Ukraine's European integration," Schulz added.