Karayilan said Turkey was using the threat of military action against the PKK to put pressure on Iraqi Kurdistan.
Ankara has been angered by a series of recent attacks by the PKK inside Turkey in which dozens of soldiers and civilians have been killed.
"It seems Turkey is preparing for an attack, then we have to resist," Karayilan said.
He was speaking from his camp in the Qandil mountains straddling the Iraq-Turkey border.
In a separate investigation by Al Jazeera, Bahuz Arzal, general leader of the PKK's military wing, said that the Turkish parliament vote was targeting "the Kurdish experience" in Iraq.
"The target of this Turkish incursion is our people in Iraq's Kurdistan, not our presence on the borderline. We assure all people not to doubt our abilities. We will work to protect ourselves and our people from any possible Turkish or other incursion," Arzal said.
PKK fighters told Al Jazeera that plans had been put in place should Turkey's military launch a cross-border raid.
"Of course there are Turkish military preparations near us, and we too have preparations. What we care about is that … we are ready psychologically and militarily for any emergency," one PKK fighter said.
Another PKK fighter said: "All our fighters are ready. If Turkey raided these posts, we would face it with all our force."
On Tuesday, Tareq al-Hashemi, Iraq's deputy president, arrived in Ankara for talks with Turkish leaders.
Al-Hashemi appealed to Turkey for more time to tackle Kurdish separatist fighters rebels based in northern Iraq, Anatolia news agency reported on Wednesday.
"Give us time to join forces with Turkey to tackle this problem, which harms the national security of both countries," Anatolia quoted Hashemi as saying.
"If the Iraqi government fails to meet its responsibilities, Turkey will be justified in doing what is necessary to protect its security interests."
Onus on Kurds
James Bays, Al Jazeera's correspondent in Baghdad, said that whatever Baghdad says, the final decision rests with Kurdish political leaders as the embattled central Iraqi government has little authority in the Kurdish north of the country.
Washington has urged Turkey to show restraint.
Ankara has long complained that neither the Iraqi government nor the US operating in Iraq have done enough to crack down on about 3,000 PKK fighters it says are based in northern Iraq.
"I think it is pretty difficult to say troops shouldn't [invade] when the Turkish soldiers are being killed and their villages attacked"
Celtic, Karlstad, Sweden
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The prospect of Turkey, a key Nato ally, sending its army into northern Iraq's Kurdish region, sent global oil prices towards a fresh all-time high of $88 a barrel on Tuesday.
Recep Tayyip Erdogan, the Turkish prime minister, said on Tuesday that securing parliament's permission to launch an attack did not necessarily mean a military incursion was imminent.
"I sincerely wish that this motion will never be applied. Passage of this motion does not mean an immediate incursion will follow," he said.
He said Turkey would "act at the right time and under the right conditions".
Barnaby Phillips, Al Jazeera's correspondent in Diyarbakir, southern Turkey, said it was highly likely the Turkish parliament would approve a military incursion into northern Iraq, which could take place at any time during the next 12 months.
"It is likely that the Kurdish minority MPs from this part of the country in the DTP [Democratic Society Party] will vote against the motion, but they will be very isolated.
"The overwhelming feeling within the parliament is nationalist and quite bullish - both within the governing AK party and within the two nationalist secular parties within the parliament."
But Erdogan also warned that the Iraqi government as well as the regional government in northern Iraq should "put a thick wall between themselves and the terrorist organisation", referring to the PKK.
"Those who are unable to distance themselves from terrorism cannot avoid being adversely affected by the struggle against terrorism."
Karayilan said PKK fighters were not crossing the border to carry out attacks on Turkish territory.
Erdogan says Turkey would act
at the right time [Reuters]
"It is not true that we are crossing the border. We have fighters everywhere. It is not necessary to send them from here.
"Their [Turkey's] aim is to attack Iraqi Kurds."
The PKK leader in Iraq said Turkey was also hoping to put pressure on the US after a congressional panel said last week that mass killing of Armenians by Ottoman Turks during World War I was genocide - a charge Turkey denies.
Turkey blames the PKK for the deaths of more than 30,000 people since the group launched its armed struggle for an ethnic homeland in southeast Turkey in 1984.