The Kurdistan Workers Party (KADEK) said on Friday the amnesty offer to rebels who surrender will not end two decades of fighting in Turkey’s south.
The outlawed group - formally known as the PKK - warned it would end its ceasefire if Ankara continued to crack down on dissident groups.
In a statement, carried by the pro-Kurdish Mesopotamia News Agency, KADEK said: "The interest of our people requires us to reject the amnesty law.
"KADEK has decided to resist all pressure and reject the law."
The amnesty, which came into force on Wednesday, is mainly aimed at members of KADEK.
The group led a 15-year armed campaign for self-rule in Turkey's south-east before announcing a truce in 1999 to seek a peaceful resolution to the conflict.
Kurds seek autonomy in Turkey's
The law offers outright pardons and sentence reductions to KADEK fighters, and nearly 600 members of outlawed groups have already applied to benefit from it.
Turkey is hoping the amnesty will help dissolve KADEK, whose fighters have retreated into northern Iraq since the group called a ceasefire.
Ankara, which considers KADEK a terrorist organisation, has already brushed aside the group's truce, and has called on the rebels to either surrender or face its wrath.
But KADEK warned on Friday that Kurdish rebels would act in self-defence to any attack directed against them.
"No matter where they come from, any attack will be met with extreme determination," the statement said.
More than 36,000 people, most of them Kurdish, have been killed in 15 years of heavy fighting between Kurdish rebels and the Turkish army.
Even though clashes have significantly abated since the 1999 truce, there have recently been signs of increasing Kurdish rebel activity in the mainly Kurdish south-east and east.
The Kurds, who say ethnic Turks discriminate against their culture and language, are seeking autonomy in Turkey's south.
However, Ankara will not countenance any threat to Turkey's unity and has brutally cracked down on its rebellious Kurdish minority.