Hanif Rezaee, an Afghan army spokesman, said that Taliban shells struck the market, situated in the Khwaja Sabz Posh district of Faryab Province.
The Taliban, he added, had been trying to hit an army checkpoint near the market.
"Fourteen civilians were killed and 40 -- including women and children -- were wounded," Rezaee said.
Meanwhile, Naem Musamim, Faryab's public health director, said that the injured had been taken to local hospitals.
Abdul Karim Yuresh, Faryab provincial police chief spokesman, stressed that the likely target of Friday’s attack was a nearby security post.
Taliban spokesman Zabihullah Mujahed, however, claimed that the mortars were fired by the government during a gunfight.
The Taliban militant group has announced the beginning of its spring offensive in Afghanistan amid peace talks with the United States and the Afghan government.