UN Secretary-General Antonio Guterres has called on the Pakistani authorities to respect due process and the rule of law in proceedings against former prime minister and PTI Chairman Imran Khan.

"The secretary-general takes note of the ongoing protests that have erupted following the arrest of former prime minister Imran Khan in Islamabad, and he calls for all parties to refrain from violence," said Farhan Haq, deputy spokesman for Guterres.

"He (Guterres) stresses the need to respect the right to peaceful assembly," Haq told a daily press conference. "The secretary general urges the authorities to respect due process and the rule of law in proceedings brought against the former prime minister."

Imran Khan was arrested on Saturday after a local court sentenced him to three-year imprisonment for hiding financial assets, which triggered protests.