There's no way you can call the murder of Lee Rigby, for example, freedom fighting. It was just plain slaughter.

I would agree, but this doesn't disprove that statement. Using several small instances of murder doesn't mean that terrorism isn't freedom fighting. That would be a categorical error.

Yet freedom of speech allows many in my country to condone it.

I see no problem with people condoning it. That is their opinion and viewpoint on the action. People in America wouldn't call the act of 9/11 freedom fighting at all, but middle eastern countries oppressed by America would probably see the act as justified revenge. Freeing themselves from the oppressing of the United States. It depends on your viewpoint. Even what society would call the most twisted viewpoints are still opinion and valued as such.

Nor could you say the Charlie Hebdo murders where freedom fighting.

I agree, but this is rather redundant.

By restricting freedom I would make people behave like decent human beings instead of animals

There is the problem. Exactly what is a decent human being? If you can answer that then what would make your opinion the objectifying truth? What would make anybody's opinion on a decent human being the objectifying truth? I use my religion as a guide, and you are entitled to use whatever you want as a moral guide, but after all is said and done our views on how humans should act will be subjective and probably unobjectionable.

You can't have both. You can't have free speech and limit it. If you want to limit it, it's not real free speech.

Which is fine, but you can't say that you think free speech is universal.