A Turkish official has denied agreement on allowing the United States to use Turkish bases for air strikes against the Islamic State group.
Earlier it was reported that the US and partners had been given access to Turkish air bases for the campaign against IS.
"We have not asked for the Turks to send ground forces of their own into Syria," US National Security Advisor Susan Rice said on NBC.
"The Turks have, this just in the last several days, made a commitment that they will in the first instance allow the United States and our partners to use Turkish bases and territory," Ms Rice said.
A US-led military coalition has been bombing fighters from IS, previously known as ISIS and ISIL, who hold swathes of territory in both Iraq and Syria.
In Syria, the main focus in recent days has been on the mainly Kurdish town of Kobane near the Turkish border.
Kurdish defenders there have been trying to halt an advance by fighters who have driven 200,000 refugees across the border.
The jihadists have laid siege to the town for nearly four weeks and fought their way into it in recent days, taking control of almost half of the town.
A UN envoy has said thousands of people could be massacred if Kobane falls.
The fighting in Kobane has taken place within view of Turkish tanks at the frontier, but Turkey has refused to intervene to help defend the city.
Turkey's inaction has infuriated its own 15 million-strong Kurdish minority, which rose up in the past week in days of rioting in which 38 people were killed.
Turkish Kurdish leaders have said their government's failure to aid the defence of Kobane could destroy Turkey's own peace process to end decades of insurgency, which killed 40,000 people.
Kobane's heavily outgunned Kurdish defenders say they want Turkey to let them bring in reinforcements and weapons to fend off the IS fighters.
The White House has said it will not allow US troops to be dragged into another ground war in Iraq, where US President Barack Obama withdrew forces in 2011 after an eight-year occupation.
The biggest army in the area belongs to Turkey, a NATO member that so far has refused to join the US-led coalition striking IS.
Turkey has said it will only join a military campaign against IS if the coalition also confronts Syrian President Bashar al-Assad.
However the US, which opposes Mr Assad but has been flying its bombing missions over Syria without any objection from his government, has made clear it has no intention of widening the campaign to join a war against Syria.
