The Islamic State group attacked the Syrian-Kurdish border town of Kobani on Saturday, but Turkey said a Kurdish claim that the militants launched the assault from Turkey was a lie.
A statement from Prime Minister Ahmet Davutoglu's office said Turkish security forces have taken "all necessary precautions" along the border.
A Kurdish official and the Britain-based Syrian Observatory for Human Rights said a vehicle used in a car bombing in Kobani had crossed over the border from Turkey.
Kurds also claimed the militants were using grain silos in Turkey from which to launch attacks on Kobani.
Ankara has consistently denied Kurdish assertions that it is cooperating with the Islamic State, saying the group is also a threat to Turkey's security.
Turkey has so far been reluctant to join the U.S.-led coalition fighting to push back Islamic State fighters inside Syria.
Fierce clashes broke out between Kurdish and IS fighters after Saturday's initial attack, which involved a number of suicide bombings. The Syrian Observatory for Human Rights said at least 25 fighters were killed in the clashes, most of them IS jihadists.
Kurdish forces, backed by coalition airstrikes, have been battling the Islamic State for control of Kobani for more than two months, with neither side gaining a big advantage.
