Speech can be restricted when it interferes with another individual. Witness tampering which includes threats of violence is illegal, so are acts which incite riots or create dangerous situation like yelling fire in a crowded building. Fake news falls under this when it is portrayed as real as well as acts of libel and such.
There are many speech acts which are not protected by free speech because their purpose is not to present a view but to prevent others from presenting their views.
Hate speech is often restricted(depends on the laws or practices) because they contain threats of violence and are meant to prevent another group from expressing their views or incite violence against them.