Dangerous rope hanging directly over cycle route

A rope has been hung from a branch directly over the middle of the cycle route. It has a small loop on the end, dangling at chin/head height of a cyclist. It is thin and blue and not easy to see, especially at night and could easily hit a cyclist in the face or at worst catch them around the chin and pull them off their bike. I was unable to cut it as I did not have the tools or get it hooked into a branch, so have had to leave it there.