"The UN has consistently called for an unequivocal end to the execution of anyone, anywhere, who is convicted of committing a crime when they are under the age of 18," a statement from the UN office in Pakistan said.
The world body also voiced concern at the Pakistani government's recent announcement that it has withdrawn its moratorium on the death penalty for all cases, not only those related to terrorism.
Among those executed there are persons who were minors when the offence was committed and more than 8,000 prisoners are on death row, the statement added.
"The UN in Pakistan urges the Government to reinstate its moratorium as soon as possible. We stand ready to support it in doing so and to assist in strengthening the existing justice system if so requested," the statement added.
The UN expressed concern over cases where the death penalty was handed down to minors but welcomed reviews of these cases.
More than 160 UN Member States with a variety of legal systems and religious backgrounds have either abolished the death penalty or do not practice it.
The UN High Commissioner for Human Rights Zeid Ra’ad Al Hussein has expressed deep regret at the resumption of executions in Pakistan, stressing that no judiciary – anywhere – can be infallible.
There is no scientific proof, according to the UN, that the death penalty serves as a deterrent or contributes to combating crime or violent extremism.
"While we appreciate the need for effective counter- terrorism measures to protect people, including children, such action must strengthen human rights and be proportionate and necessary in a democratic society," the UN said.
Under international treaties, in particular the International Covenant on Civil and Political Rights and the Convention on the Rights of the Child, Pakistan legally committed itself to ensuring due process and not imposing the death penalty.