Dadullah Mansur made the remarks in an audio recording played on June 1 at a rally at Killi Nalai, a village about 75 kilometers west of Quetta, near the Afghan border.
Abdul Sattar Chishti, the cleric who organized the event, said more than 12,000 people listened to the speech.
Dadullah Mansur is the brother of Mullah Dadullah, the top Taliban commander who was killed in a U.S. operation last month in southern Afghanistan.
In Afghanistan, Taliban militants reportedly attacked a local police commander's home early today, killing five of his family members and sparking a gun battle with police that left 10 insurgents dead.
The attack in the southeastern province of Ghazni killed the commander's wife, two sons, and two nephews, according to Interior Ministry spokesman Zemeri Bashary.
Other police called to the scene battled the insurgents, killing 10 of them.