The envoy said that Pakistan will participate in the Moscow-format consultations on Afghanistan in October.
In a statement, the rights group said millions of Afghans are being forced to leave host countries, where many face arbitrary arrests and family separations.
Sharif said Pakistan has remained one of the world's largest refugee-hosting countries and has managed the welfare of millions of Afghan nationals throughout this period.
Regional police chief Liaqat Ali Malik said four officers had been killed and 97 wounded in clashes with protesters, while 515 people had been detained.
The project includes approximately 760 kilometers of new railway construction inside Afghanistan, between Mazar-e Sharif and Torkham.
The development may signal that both sides intend to begin technical negotiations aimed at securing a permanent truce.