An assembly of roman citizens who governed rome?

The popular assemblies did not govern Rome. During the period of the Roman Republic (509-27 BC) they were voting bodies. The Assembly of the Soldiers voted on war and peace and elected the senior executive officers of state (the consuls, praetors and censors). The Assembly of the Tribes elected the junior officers of state (the aediles and the quaestors). The Plebeian Council elected the plebeian tribunes. In the Early Republic, the Assembly of the Soldiers voted on bills. Later this role was taken over by the Plebeian council.

The government of Rome was made up of the five types of officers of state mentioned above. Except for the censors, who were elected every 18 months, they were elected annually. They acted independently within the remit of theory offices. The Republic did not have a centralised government, like an administration or a cabinet. The consuls were the heads of the Republic.