"We are not happy with the quantum of punishment that has been given to the accused. We feel that the quantum has diluted the message," Aman's father Rajendra Kachroo said in a statement.
A fast track court in Dharmsala, Himachal Pradesh held all four accused in the ragging case guilty of culpable homicide not amounting to murder on Thursday, Nov 11. The court sentenced them to four years in jail.
19-year-old Aman died in March 2009 after being ragged by four senior, who were drunk at the time.
Stating that one of four accused had a "violent background", Aman's father said, "He started the entire episode and was the leader of the gang. He should have been given severest punishment. There should have been a distinction created between the ringleader and the rest.
"We will certainly consult the public prosecutor and request him to appeal against the quantum of punishment."