Other concerns have been raised over reports three volunteers with a Westminster-based women's safety programme had been
arrested while handing out rape alarms.
The Met said it received intelligence protesters were planning to use rape alarms to disrupt coronation proceedings.
Ms Frazer said the right to protest was "really important" and people should be heard but there had been a recent change in protesters' tactics.
Protesters have been stopping people going about their day-to-day lives, she said, and there was a need to redress that balance.