Look, the best thing to do is just avoid the fight. Dont even say anything. Personally I have better things to do with my time than to get into fights, but I know that sometimes you can't avoid them. And when you can't avoid them as long as they hit you first, you cant end up in trouble.
I got dragged through the courts for a fight that I was trying to avoid.
I had a big gripper trying to pick a fight with me in a pub, he got thrown out, I stayed in the pub, later on he followed me down a lane to a bus stop and started going for me when I was sitting down on a chair, I managed to dodge the punchs but then he went even more crazy at me so I hit him with the closest thing that came to hand, which happened to be a bottle.
I ended up in the cells, and having to defend myself at crown court for GBH.
I was found unanimously not guilty, as it was self defence, but one things for sure, the exprience of having to go back and forth to courts for a year and into police stations isnt a nice thing to have to go through. So my advice to you. Just ignore them and carry on with what ever you're doing.