Qadri was flying to Pakistan to lead what he describes as a revolution against Prime Minister Nawaz Sharif.
His plane circled above the capital for hours as thousands of his followers tried to get to the airport to greet him.
Supporters became angry after police blocked roads, preventing them getting there. Mobile phone networks were jammed, stopping them communicating with each other.
One police officer was badly beaten by the crowd.
Qadri’s plane was eventually diverted to Lahore where he refused to get off. He demanded it fly back to Islamabad.
A Qadri spokesman said the former cleric wants to stage an Arab spring-style revolt and install a government that would enforce reform and tackle terrorism.