The situation I got told off for was I was stationary in traffic on a busy main road, and a pedestrian had crossed half-way (not on a proper crossing or anything) and was trying to cross my side of the road. I could see 50 yards ahead there was a traffic light at red so I couldn't continue...
I got told off by my driving instructor for doing that. The reason being it is not safe for me to wave a pedestrian over when I can't account for other drivers actions that may hit them.