Turkish Presidential Spokesperson Ibrahim Kalin said Thursday in a press briefing that Turkey has good relations with both Baghdad and Arbil but a referendum would have "consequences".
"The United States does not support the Kudistan Regional Government's intention to hold a referendum later this month", the White House said in a statement.
The referendum is planned to be held in Kurdistan and disputed areas including the oil-rich province of Kirkuk.
Gorran, the main opposition movement to Barzani's Kurdistan Democratic Party (KDP), boycotted the parliament session in Erbil.
The non-binding referendum is planned to see residents in provinces controlled by the KRG vote on independence from Baghdad on September 25.
KRG leader Masoud Barzani on September 15 said that the referendum will be held as planned despite objections from Baghdad, Turkey, the United States and other Western nations.
Kirkuk is home to sizeable Arab and Turkmen populations and lies outside the official boundaries of the Kurdistan region.
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Voters will face one question, asked in Kurdish, Arabic, Turkmen, and Assyrian: "Do you want the Kurdistan Region of Iraq (KRI) and Kurdistani territories that are outside KRI to become an independent state?"
Iraq's central government has rejected the polls as unconstitutional and illegal.
In recent years, there have been tensions between Baghdad and Kurdistan over power-sharing, oil revenues and territorial disputes.
Barzani criticized those claiming that referendum does not have legitimacy, saying "the referendum's legitimacy comes from the people of Kurdistan".
The vote was to give a legal framework to the referendum that has also stirred protests from neighboring states, especially Turkey.
Iraq's Kurdish region has enjoyed a high degree of autonomy since the USA imposed a no-fly zone over northern Iraq after the 1990 Gulf War.