Amnesty International also urged the president on Friday to take the necessary steps to commute the death sentences handed down to them.
"The finality and cruelty inherent in the death penalty, and the lack of evidence showing it to be a deterrent to violent crimes, make it an inappropriate and unacceptable response to crime," said Amnesty International in a statement.
The executions are due to take place at Roumieh prison in Beirut. Ahmad Mansur is to be executed by hanging, while Badi Hamada and Remi Zatar are to be executed by firing squad. Neither family members nor the media are allowed to witness the executions.
Mansur, is charged of killing eight co-workers in July 2002, while Zatar, is convicted of killing two members of the civil defense and a Syrian army officer in June 2002. Badi is a Sunni Muslim fighter accused of killing three Lebanese soldiers in the summer of 2002.
The human rights watchdog said executing these individuals will contribute little to alleviating the suffering of the families of murder victims
"The finality and cruelty inherent in the death penalty, and the lack of evidence showing it to be a deterrent to violent crimes, make it an inappropriate and unacceptable response to crime."
The watchdog went on to say that "Beams of hope lit by a de facto five-year moratorium on the death penalty have been dimmed by Lebanon's decision to kill these men."
The last executions in Lebanon were of two murderers in May 1998, both hanged in public. Until then, no capital punishment had been carried out for 15 years.
"Their lives and those of 24 others under sentence of death whose fate may well be similar are now at the gravest risk imaginable, and no effort should be spared to save them," it added.
Despite strong protests from local and international human rights campaigners and groups, Lahud signed the final execution decrees on 14 January.
When Lahud took office, his prime minister of the time, Salim Hoss, was an opponent of the death penalty and refused to sign any orders for execution.