Khan, 70, was leading a protest march in Islamabad to demand snap elections.
Pakistan International Airlines spokesman Abdullah Hafeez said "the situation on the ground is not conducive for international flight operations."
Trump failed to host the White House Iftar dinner for Muslims held every year since 1995.
Despite heavy U.S. airstrikes of the mountain lair, al Qaeda terrorists escaped into Pakistan.
Mumtaz Qadri killed Salman Taseer in 2011 for criticizing Pakistan's strict blasphemy laws.
Women make up just over a fifth of Pakistan's workforce.
Islamabad will not sanction support for Saudi airstrikes over concerns of stoking anti-Shia sentiment, say analysts.
Anti-government protesters seized a national TV channel after clashing with authorities in Islamabad
Khan's vehicle was hit as tens of thousands of protesters from two anti-government movements converged on Islamabad with security tight