https://en.wikipedia.org/wiki/Freedom_of_speech See the limitations part.
Also I find interesting that the right to privacy (which I value a whole lot) is a restriction of free speech. Depending on the context (as nearly always), I'm perfectly fine with that.
Allowing unrestricted free speech is at least as dangerous as heavily restricted free speech. Like many things in real life, it's too complex to just be either all black or all white, but more like shades of grey.
