Prime Minister Binali Yildirim made his comments to a group of Turkish journalists after announcing that US Vice President Joe Biden would visit Turkey on August 24, Reuters reported.
The 75-year-old Gulen, who has lived in self-imposed exile in Pennsylvania since 1999, denies any involvement in the failed coup.
The fallout from the abortive coup, in which more than 230 people were killed as mutinous soldiers commandeered fighter jets, helicopters and tanks in a bid to seize power, has deepened a rift between Ankara and its Western allies.
Erdogan and many Turks have been frustrated by US and European criticism of a crackdown in the wake of the putsch, accusing the West of greater concern about the rights of the plotters than the gravity of the threat to a NATO member state.
More than 60,000 people in the military, judiciary, civil service and education have been detained, suspended or placed under investigation since the coup.
"If we have mercy on those who carried out this coup attempt, we will be the ones to be pitied," he said.