The United States "does not recognize" Iraqi Kurds' "unilateral" referendum on independence and calls on all parties to reject the use of force and engage in dialogue, Secretary of State Rex Tillerson said Friday.

"The vote and the results lack legitimacy and we continue to support a united, federal, democratic and prosperous Iraq," he said in a statement.

"The United States asks all parties, including Iraq's neighbors, to reject unilateral actions and the use of force."