The explosion took place in the Kabal area of Swat, a district in Pakistan's Khyber Pakhtunkhwa province on Sunday.
A pro-police rally of local residents was taking place in the same area on Sunday, where demonstrators chanted anti-militant slogans and demanded peace, district police chief Omar Khan said but it was not immediately clear whether the rally was the intended target.
According to witnesses, shortly before the attack, speakers at the rally said that ensuring security and eliminating militancy were the state's responsibility.
They also accused authorities of failing to act decisively against militants, saying residents wanted to live without fear after years of violence that devastated the region.
Fida Hussain, a regional police official, said the victims included five police officers and eight civilians. The 14th person was believed to be the suicide bomber, he told Reuters.
At least 18 people were wounded, according to a police statement. It said an operation had been launched to arrest anyone who may have assisted the attack.
The Tehreek-e-Taliban Pakistan militant group in a statement claimed responsibility for the attack.
Prime Minister Muhammad Shehbaz Sharif in a statement expressed "deep grief and sorrow over the suicide blast".
Militancy in Pakistan's border areas has risen sharply in recent months, targeting mainly the military and police.
The Pakistani government blames the Afghan Taliban for the escalation, accusing it of providing support to the militants. The Taliban government has denied the accusations.
with AP
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