In a post on Twitter, Nujaba spokesman Nasr al-Shamari said that the two martyrs had done nothing but seeking freedom, justice, dignity and liberation from oppression.
He added the Saudi rulers should realize that shedding every drop of blood to strengthen their rule will only bring their end closer.
On Monday, Riyadh announced the execution of two Bahrainis named Jaafar Muhammad Sultan and Sadiq Majeed Thamer.
This brought the total number of executions in the kingdom to nine this month.
The two were charged with “joining a terrorist cell aimed at destabilizing the security” of Saudi Arabia and Bahrain, a Saudi interior ministry statement said.
It claimed that the two had been trained to create chaos and carry out acts of sabotage in the kingdom.