Irfan tried to commit suicide by immolating himself this morning, city SP Man Singh Chauhan said.
He was was rushed to a hospital where his condition is now stable, police said.
Denying "any sort of pressure" on Irfan because of police interrogation into Siras' mysterious death on April 7, Chauhan said that the rickshaw pullar was "apparently under severe financial pressure", which could have led to the suicidal act.
The body of 62-year-old Siras, a reader in Modern Indian Languages, was found on the bed in his private apartment outside the university.
Siras, who hailed from Maharashtra and taught Marathi, was placed under suspension by AMU Vice Chancellor P K Abdul Aziz on charges of homosexuality at his house inside the campus after a sting operation by a television channel which exposed him having sexual relations with a rickshaw puller.