Jens Stoltenberg also warned Turkey that its bombing campaign could endanger the progress that has been made in recent years towards reaching a peace deal with Kurdish militants.
NATO ambassadors are due to meet tomorrow at Ankara's request to discuss the spike of violence between Turkey, Islamic State jihadists and Kurdish militants.
"Turkey has a very strong army and very strong security forces. So there has been no request for any substantial NATO military support," Stoltenberg said in an interview with the BBC on Sunday.
It has also bombed positions of the Kurdistan Workers' Party (PKK) in northern Iraq for the first time in four years, after the militants, who accuse Ankara of colluding with the Islamists, claimed the killing of two police officers.
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While applauding Ankara for joining the fight against the IS, the NATO chief cautioned that "self-defence has to be proportionate".
And in an interview with Norwegian television late Sunday, he warned that Turkey's strikes on Kurdish militants risked undermining years of tortuous peace talks.
Turkey regards the PKK, which has waged a deadly insurgency in southeast Turkey since 1984, as a terror group and the main Syrian Kurdish group fighting IS -- the Democratic Union Party (PYD) -- as the PKK's Syrian branch.