The man, named locally as Kevin McGuigan Snr, was shot dead at Comber Court in Short Strand on Wednesday (August 13) around 8.55pm. He later died from his wounds at the Royal Victoria Hospital.
Mr Lyttle said there was no place for murder and violence in society.
“Such acts must be condemned, no matter who the victim was. A callous and coldblooded attack has left a man dead and a family in grief. We need to be clear that for people to take the law into their own hands is always unacceptable.
“The perpetrators of this attack must be brought to justice and swiftly. I would appeal for an end to all criminal activity in our society and for people to respect the rule of law, with no retaliation.
“Anyone with information on this heinous attack must go to the police with it immediately.”