Turkish artillery fired shells from howitzers positioned on its border region of Kilis against IS targets, the private NTV television reported.
Meanwhile, more than one rocket fired from the Syrian side of the border hit the centre of a Turkish town, a Turkish government official told AFP.
The official did not say who fired the rockets which slammed into the centre of Kilis -- the main town in the province of the same name -- near the Syrian border and left more than four people wounded.
The injured were taken to hospital in ambulances, he said.
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The Turkish army's shelling of IS targets comes after the extremists took back control of the town of Al-Rai near Turkey, which rival rebels had captured last week, the Syrian Observatory for Human Rights said.
Neither the Al-Qaeda-affiliated Al-Nusra Front nor IS are included in a truce brokered by the United States and Russia that came into force on February 27.
In February, Turkish artillery had also shelled targets of the Syrian Kurdish Democratic Union Party (PYD) inside Syria, with the military saying it was responding to incoming fire.
But Turkey has not shelled any positions held by Syrian Kurdish fighters inside Syria since the ceasefire was implemented.
Washington has applauded Turkey's role in the anti-IS coalition but US officials on occasion have urged Ankara to do more.