The 25-year-old, who joined the Toffees from Olympiakos last summer in a £6m deal, has featured in the last six games having shaken off a hamstring problem.
But speaking ahead of Saturday's trip to face Norwich, Moyes said of Mirallas: "I don't think he is firing on all cylinders.
"He has not returned the way I would like him yet. He is still getting used to the Premier League and I think he has to create me more goals and score me more goals.
"That is what I am waiting for him to do, and he knows that - I have told him that. We are hoping for more.
"I think his form at the start of the season was excellent and we saw what he was capable of. I don't think we have really had that from him since he came back from his injury."
It is not just Mirallas who needs to up his game according to Moyes - but fellow hitman Nikica Jelavic, too, with the Scot adding: "We need Niki to come back into it.
"He was a big player for us this time last year, scored a lot of goals and did a good job. That is what we could with now, him coming up and giving us the goals.
"I don't think we've played too badly - in fact, I think we have played quite well, and in a lot of the games we've maybe just been missing a little bit of the edge to get us the goals."