Geelani, who has been placed under house arrest in the national capital, said before his detention that it was an "unfortunate" decision to hang Guru.
Claiming that Guru was not involved in the 2001 Parliament attack, Geelani said he had also not been given a chance to defend himself in the case.
He said a strike call had been given for three days and may be intensified later if the body of Guru was not handed over to his family members.
Geelani also condemned the curfew imposed in Kashmir Valley after Guru's hanging.