The club are looking for attacking reinforcements after letting Sebastien Haller leave for £22million earlier in the month.
Michail Antonio is the only recognised striker, and on Saturday scored in only goal as Burnley were beaten.
Reims striker Boulaye Dia is a key target, with Arsenal unwilling to let Eddie Nketiah leave. A move to bring Marko Arnautovic back is unlikely due to his wages in China.
"We've already made big enquiries and offers for players with clubs," Moyes told reporters. "They've obviously not been accepted otherwise I would have someone.
"It is not as if we're not trying to do that, we have tried. I need to try and get players who I think would make a difference and I want it to be something which I think can help us.
"If I don't I might need to look short term, just to get me through to give me another player but if not then I'll use the young players or I'll have to try and find us a centre-forward from someone else in the squad.
"If Mick can regain his real form and where he has been in recent months that would be the big thing for us. He is getting closer, another 90 minutes and a goal. It is what we have really missed so we're glad to have him back."