Cemil "Cuma" Bayik, the de facto leader of the Kurdistan Worker's Party (PKK), said: "We have the right to launch attacks against Iranian forces."
The PKK has fought Turkey for years in its battle to establish an independent state in the majority Kurdish southeast of the country.
He said recent Iranian artillery shelling of PKK camps in Iraqi Kurdistan meant that the rebel group's battle could spread to Iran.
"We are on the defence. If we're not attacked we won't either. We believe politics and democracy are a better path," Bayik said.
But Bayik said PKK "intelligence reports" suggested that Iran was preparing to shell rebel positions again.
"We aren’t capable of facing them in open battle. We'll make hit-and-run raids with our Kalashnikovs, rocket-propelled grenades, machine guns and mortars," he said.
The PKK consists of thousands of male and female Kurdish fighters who profess a "democratic socialist" philosophy, under which women's equality plays an important role.
To join, members have to renounce material possessions and cut links with the outside world in their quest for Kurdish independence and a new social order in which women will no longer be "enslaved", Bayik said.
Turkish Kurds are fighting for an
independent state in Turkey
Bayik saw the offensive by Iran as part of a devious strategy by Iran. He said it was born of Iran's desire to please Turkey, its neighbour and a Nato member, as Western pressure mounts over Tehran's nuclear programme.
"They will do anything to make sure Turkey is not with the US in a fight against Iran," said Bayik, who commands the rebels in Iraq and Turkey while PKK founder Abdullah Ocalan serves a life sentence in a Turkish prison.
Turkey applauded the attacks against the PKK camps, which lace a series of steep winding valleys in a region close to Turkey and Iran where the adjoining territories are all majority Kurdish.
An estimated 25 to 35 million Kurds live in Iran, Iraq, Turkey and Syria.
Ankara has long urged Iraqi and US forces to root out the PKK from Iraq's northern region, which they have occupied since the war between Iran and Iraq in the 1980s.
Turkey says that about 5,000 PKK fighters have found refuge in northern Iraq since 1999.
Bayik said the figure was lower but would not provide a specific number, saying it was a "military secret".
He said the Iranian attacks were also intended to put pressure on Baghdad as it struggles to form a government.
"We are not against the PUK having good ties with the Turkish and Iranian governments but these relationships should not go against the Kurdish nation."
Cemil "Cuma" Bayik, the de facto leader of PKK
Kurdish leaders in Iraq have promised to work to integrate the oil-rich Iraqi city of Kirkuk into a Kurdish autonomous zone after a cabinet is formed.
Bayik said Iran is "trying to help some factions in Iraq work against the Kurdish nation so that Kirkuk doesn't join [the autonomous zone]".
"This is happening as the new government is being created and the Kirkuk problem is discussed," he said.
But on Friday, Iraqi Kurdistan's Sulaimaniyah province administrator, the Patriotic Union of Kurdistan (PUK), warned the PKK against using Iraqi territory to attack Iran or Turkey.
"They should think of all of Kurdistan," Bayik said.
"We are not against the PUK having good ties with the Turkish and Iranian governments, but these relationships should not go against the Kurdish nation."