A few hundred Khan supporters gathered outside his house after a police team arrived from Islamabad to arrest him on a court order, government spokesman Amir Mir told Reuters.
Khan's Pakistan Tehreek-e-Insaf (PTI) workers started the violence, which injured several police officials, Mir said, adding, "If Imran Khan ensures his presence in the court, it will be good, otherwise the law will take its course."
"If something happens to me, or sent to jail, or they kill me, you've to prove that this nation will continue to struggle even without Imran Khan."
Several of Khan's supporters were injured when the police resorted to teargas shelling, witnesses said.
The workers started pelting the police with stones and bricks, and in response police directed a water cannon at them and in some cases baton charged them, he said.