Afrasiab Khattak, the party’s provincial leader and a prominent human rights champion, was addressing the rally but told Dawn television that he was not hurt.
Nawaz said Islamic militants were threatening all the political parties in the northwest ahead of the Feb. 18 parliamentary elections.
“They are against everyone,” he told Dawn News TV.
Charsadda has witnessed several attacks in recent years.
More than 50 people died there in December when a suicide attacker detonated a bomb amid hundreds of holiday worshippers at a mosque at the residence of former interior minister Aftab Khan Sherpao.
Elsewhere on Saturday, a roadside bomb wounded six paramilitary soldiers in southwestern Pakistan, police said.
The attack happened at Naushki, about 150 kilometres southeast of Quetta, the capital of southwestern Baluchistan province. (AP)
Suicide bomber kills at least 18 at election rally in Pakistan