How To Stop Kids Walking Along My Garden Wall And Knocking Down Plants?

There is a 4ft wall that runs along the back of all the gardens in my street. There is also a fence that starts where the wall stops but it’s a few inches away from the wall so it makes the wall perfect for walking right along the back of all the rear gardens. I have a few window boxes along my part of the wall with climbing plants to go up the fence (to give us a bit of privacy from the two blocks of flats behind it) but for the past few nights a couple of boys (around 10-11) have been getting in through someone elses garden up the street and walking right along the wall through all the gardens and take great pleasure in knocking my pots down along the way.
I have tried to make the garden lovely for my family-especially the kids to enjoy and also have a summer house and a couple of sheds with expensive garden equipment and the kids bikes, a big slide and swings etc. I’m worried the little brats will do more than just knock my plants over-although this alone is driving me nuts! thanks