He said the recommendation on the mercy petition of 32-year-old Singh will now be sent to the Union Home Ministry.
The decision comes a day after Singh filed the plea.
"We learnt that a petition has been filed and we have recommended its rejection and sent it at lightning speed to the LG. There will be no delay from our side, we can assure you that," he said in response to a question.
The Delhi High Court Wednesday declined to entertain Singh's plea against the death warrant issued by a trial court and gave him the liberty to challenge it in sessions court.
A bench of Justices Manmohan and Sangita Dhingra Sehgal said there was no error in the trial court's January 7 order issuing the death warrant against him.
The Delhi government informed the high court during the hearing that execution of the convicts will not take place on January 22 as a mercy plea has been filed by one of them -- Mukesh Singh.
The four convicts -- Mukesh (32) Vinay Sharma (26), Akshay Kumar Singh (31) and Pawan Gupta (25) -- were to be hanged on January 22 at 7 am in Tihar jail. A Delhi court had issued their death warrants on January 7.