Fifteen members of a group Respect the Flag face street gang charges from the incident near Atlanta in late July.
Pick-up trucks decorated with the Confederate banner drove past the party in Douglasville and shouting broke out.
Residents told local media the people in the trucks used racial slurs but they say they were attacked.
On Monday the Douglas County district attorney’s office said that, following an investigation, the individuals from Respect the Flag were being charged with violating the state’s law on street gangs and with making “terroristic threats”.
Two of them are also charged with battery in relation to a separate incident at a petrol station the same day.
The Confederate battle flag became a potent symbol for the southern states fighting the Civil War and is seen by some as an icon of slavery and racism.
Earlier this year, there was renewed debate in the US about its place on public buildings after a man accused of killing nine worshippers at a black church in South Carolina appeared in many photos holding the flag.