Yep, it’s one of those dialogue examples…
Smirking doesn’t make any sound whatsoever. It’s not a form of vocalization, so no one can smirk any words at all.
“You’re such a human!” he said, smirking.
“Did you just call me a human?” I growled.
You could also write the first line thus: “You’re such a human!” He smirked. That makes the speaking and the smirking sequential rather than simultaneous actions. It has a choppier flow than the previous version (which may or may not be desired), but it leaves the original wording intact.
Your’e? Really? *rolls eyes* Hedging your bet with apostrophe placement never works.
Also notice that he is not capitalized in the first corrected version. Be alert for auto-correct that wants to capitalize the first word after an exclamation point even when that punctuation ends only the dialogue, not the sentence as a whole.
(FYI: Some people wouldn’t take offense at being called a human; some people would take it as reassurance that their disguise was still working.)