Speaking to reporters, Gul said: "[The army] was granted a mandate. This mandate is being used when [the army] deems it necessary."
Turkey said it carried out an "intense intervention" in northern Iraq on Saturday, sending in about 100 special forces.
Long-range artillery and up to six helicopters bombed a PKK camp after spotting a group of up to 60 fighters 20km inside the border, a Turkish military official said.
The army said on Sunday that two PKK fighters had also been killed on Saturday in clashes in southeastern Turkey's Sirnak province, on the border with Iraq.
Another two were killed in fighting in the town of Eruh, in Siirt province, just north of Sirnak, the state-run Anatolia news agency reported.
Cemil Cicek, the deputy prime minister, made clear that operations in northern Iraq would continue as the military saw fit.
In an interview with broadcaster Kanal 24, he said: "The Chief of general staff decides and will decide the necessity and timing of [the operations].
"If the goal is met with one operation, then one operation will be done. If 10 operations are needed, then 10 operations will be done."
But Jabbar Yawar, a spokesman for Kurdistan's Peshmerga security forces in Iraq, said there had been no incursion or shelling by Turkish forces into northern Iraq.
A PKK leader, however, acknowledged that separatist fighters had come under attack by Turkish helicopters inside Iraq but insisted they had suffered no casualties.
The commander had initially denied any attack, but on Sunday told AFP news agency: "There were helicopter strikes along the border, but we suffered no casualties."
He said the PKK is "keen to resolve the crisis" and urged Ankara to consider a conditional ceasefire offer made by the group in October after separatists ambushed and killed 12 Turkish soldiers.
Turkey rejected the ceasefire offer and received parliamentary authorisation in October to launch military action against the PKK inside Iraq.
Ankara has massed up to 100,000 troops near the mountainous border with northern Iraq, backed by tanks, artillery and warplanes ahead of a long-awaited strike against PKK fighters who use bases in northern Iraq to launch attacks in Turkey.
On Friday, Recep Tayyip Erdogan, Turkey's prime minister, said the cabinet had authorised the armed forces to conduct a cross-border operation.
Ankara has made many threats of military action but, under heavy US pressure, has so far shown restraint.
Cengiz Aktar, a Turkish political analyst, told Al Jazeera: "Apparently these are routine operations. Surgical pinpointed operations that will take place in the course of the next 11 months that the Turkish army was granted by the civilian parliament [to do so].
"That was cleared ... during the meeting between Prime Minister Erdogan and President Bush on November 5.
"We don't expect a big operation, but we might have limited operations.
"This one looks more like a PR [public relations] exercise, because the US military even denied it took place.
"The Americans would hate the idea of seeing another type of chaos in Iraq ... As for today, we don't see any opportunity for the Turkish army for a major and massive land operation."
Washington fears a major attack would create chaos in Iraq's most stable region and possibly further afield.
About 3,000 PKK fighters, seeking a separate Kurdish homeland in southeastern Turkey, operate in northern Iraq. Ankara blames the PKK for the deaths of nearly 40,000 people since it began its armed struggle in 1984.