I'm not sure if I'm being a bit PFB and need some perspective (I suffer social anxiety and I find it very difficult to know how to react to situations).
PFB is 5; she goes to a tumble tots type class . There is a girl in this class who is a year older than dd.
We hardly know her but have talked to her parents a few times at the class as the girls seemed to play together .
It has become apparent that this girl is quite rough in her play and is starting to really get on my dds nerves - as well as mine .
She appears to have no social boundaries - she thinks nothing of trying to sit on my DH lap at the class , or wrapping her arms around my waist whilst her parents do nothing .
In yesterday's class , this girl physically hurt my dd on more than one occasion . I don't think she is being malicious - more over excited and far too rough .
In the space of 45 minutes , she "bopped" my dd on the top of the head hard , pushed her in to another child and grabbed her arm leaving a mark .
When this happens , my dd tells her to stop and the girl seems oblivious 
My dd is petite and I got really frustrated watching this today .
The issue is , as both girls are at the same stage , they can't be moved to different groups . As the girl is not being malicious as such and appears to be playing , I can't see it making any difference if the class teacher has a word - especially as she is not going to be able to watch all of the time .
I don't want to cause a fuss , but I also don't want to allow my dd to keep getting hurt
I could tell today , it is starting to bother her .
Dd has asked me to tell the class teacher . I said I would but explained that it won't be possible to be separated , but the teacher should keep an eye on it .
How should I approach it ? I'm friendly ish with the teacher - should I text her and mention it or wait until the next class and mention it or should I tell dd to tell the girl firmly to stop ?
Part of the problem is that dd is happy to play with the girl , but then it gets rough and the cycle is repeated .
I don't want my dd to think I won't protect her , but on the other hand , I don't want to cause a fuss over something that is unlikely to change , unless dd keeps away from this girl .
Help !