The woman was on her way home from work when she encountered the group in the underpass beneath the A61 at Meadowhead.
She says she was subjected to a stream of vile, foul-mouthed abuse and had bottles thrown at her as she tried to pull one boy who was bleeding heavily from the fracas.
In a Facebook post, she said: “The mum guilt kicked in and I went to separate them – I’d hate it to be one of my kids.
“They separated and I made sure the boy who had blood p****** out of his nose was OK, whilst dodging the other lads’ punches.”
She was then met with “various other lads who continued to hurl abuse at me and tell me to f**k off b**ch and mind my own business!”
"The lad was alright and I went on my merry way, to then be called every name under the sun and have bottles thrown at me whilst simply just seeing if someone was alright was something else.
“The language was disgusting the abuse was damn right awful and to them boys, you should be so proud of yourselves you are gonna go far in life.”
She said the incident took place at about 3pm with “in excess of 30 kids under the subway, all stood around in a circle” and that it was “pretty obvious there was going to be a fight.”
She added: “So if your kid comes home with a bloody nose please feel free to get in touch - I’ll be more than happy to identify the little t**** that did that to your son.
“If your kid was there, you should give them a wake up call. To speak to someone and hurl the language they were at me was something else.
“Please get in touch if you would like to know if your kids were there I’d be more than happy to tell you.”