Usman Buzdar, chief minister in Punjab province, said in a tweet that the violent clashes left four police dead and 253 injured.
Khan's decision infuriated supporters of the Tehreek-e-Labiak Pakistan party who over the weekend suspended their march to Islamabad to give the government three days to consider their demands.
The violence erupted a day after the government of Prime Minister Imran Khan said it would not accept the Islamists' demand to close the French Embassy and expel the French envoy.