Less of something (British English Probably)
Yes. The imperative expression "less of ..." means both less and stop.
It is a form much loved of school teachers to mean "If you are unable to moderate the behaviour that you know is not permitted, then I will be required to take direct action to stop it entirely. We share the implicit understanding that I do not wish to take that action, but I will if necessary".
Failure to respond to the original instruction can lead to the equally incomprehensible "All right. I warned you. Cut it out."