The death toll from the Gaziantep attack rose to 50 early Sunday, according to the local governor's office.
President Recep Tayyip Erdogan said there is "no difference" between three opponents of his government: terror group ISIS, which is based in neighboring Syria; the outlawed Kurdistan Workers Party (PKK); and FETO, the network of US-based cleric Fethullah Gulen
, state-run Anadolu news agency reported Sunday.
Erdogan accuses Gulen of being behind a recent coup attempt. He has denied the accusation.
No group has claimed responsibility for the attack, which also injured 94 others.
The blast occurred in the city of Gaziantep, about 95 kilometers (60 miles) north of the war-torn Syrian city of Aleppo.
The agency added that the wedding celebration took place on a street, which is common in southern Turkey.
Video of the aftermath shows hundreds of people in the darkened street as rescue workers lift victims into ambulances. Orhan Akin, Gaziantep bureau chief for the Ihlas News Agency, told CNN Turk that he saw "at least 20 ambulances carrying injured people."
Earlier, Erdogan condemned the attackers.
"Those, who cannot overcome Turkey and try to provoke people by abusing ethnic and sectarian sensitiveness will not prevail," Anadolu quoted him as saying.
Turkey has experienced significant turmoil in recent months, with the attempted military coup in July and a series of deadly explosions.
Past attacks have been carried out by ISIS, which controls northern Syria across the border, and the PKK.
In the most brazen attack, 44 people were killed in July by suspected ISIS suicide bombers at Istanbul Ataturk Airport.
Last March, two suicide bombers killed at least 40 people in Ankara, the capital. A Kurdish rebel group claimed responsibility for that attack.
On August 10, two explosions killed at least eight people in the southeastern towns of Kizitepe and Diyarbakir. Initial assessments indicated Kurdish militants were behind both attacks, a government official said.