I think you mean Geneva Convention and the answer to that is generally, no. The Romans did not have a code of ethics that are familiar to us today. However, the "ancient Romans" span a time period of over a millenia, during which Roman warfare changed dramatically.
I will first look at the Romans during the middle Republic. This is the period when Romans slowly, then rapidly, dominated the Mediterranean and I will use the third Punic War as an example of Roman warfare. The third Punic War was for all intents and purposes, unnecessary. The Romans already proved their dominance over the Carthaginians in the second Punic War. The third Punic War was then not fought in self defense but for glory and greed. In the culminating siege of Carthage, hundreds of thousands of Carthaginians died with the rest being taken as slaves. Many modern scholars considered this to have been a genocide of the Carthaginian civilization.
Now I will look at the Gallic Wars right at the end of the Republic. Julius Caesar's conquest of Gaul was both efficient and brutal. He himself claimed to have enslaved one million people and his Commentarii de Bello Gallico has many instances where he razed towns to the ground and annihilated tribes (notably the Eburones). Again, the Roman people generally had no qualms about any of this and his Commentarii de Bello Gallico was made to boost his image.
Finally, I will look at the Septimius Severus's wars in Caledonia, at the end of the Principate. This war was characterized by rebellion and guerilla warfare as Septimius Severus tried to conquer the unruly tribes north of Hadrian's Wall. When the Caledonians revolted after having been in 210AD, Septimius Severus ordered the extermination of the Caledonians, purportedly saying "Let no-one escape sheer destruction, no-one our hands, not even the babe in the womb of the mother, if it be male; let it nevertheless not escape sheer destruction." While this was never carried out to its full extent since Septimius Severus died quickly after the order, there is no doubt the Romans fully intended to commit genocide against the Caledonians.
So, no matter which period in Roman history, there are clear instances of horrific acts of war committed by the Romans. However, it should be noted that Romans were not somehow special in this; ancient civilizations are constantly raping, pillaging, and enslaving their neighbors.
Sources:
Caesar, J., & Lowe, C. M. (1907). Caesar's Gallic war. Scott, Foresman.
Dio Cassius (Xiphilinus) ‘Romaika’ Epitome of Book LXXVI Chapter 15
Kiernan, B. (2004). The First Genocide: Carthage, 146 BC. Diogenes, 51(3), 27–39. https://doi.org/10.1177/0392192104043648
Rodgers, N., & Dodge, H. (2006). Roman empire. Lorenz Books.