Moyes only managed to secure the ?27.5million deadline-day purchase of Marouane Fellaini from old club Everton during the summer and there has been general acceptance he will attempt to bolster his United squad at the first opportunity.
However, that may not end up being the case.
"Only if the right players are available," he said. "They have to be able to fit into our squad. We would like to but there are no guarantees."
Moyes attempted to prise left-back Leighton Baines out of Goodison Park without any reward and his successor as Everton manager, Roberto Martinez, has already said another attempt would be pointless.
"If they are determined to hold on to him then he can't be going anywhere," said Moyes.
Moyes was giving little away over Nemanja Vidic and Robin van Persie, who both missed the 5-0 win at Bayer Leverkusen in midweek, stating: "They have got a chance."
However, with Wayne Rooney in superb form, the Scot does believe he has an attack to rival any in the Barclays Premier League.
"I have been asked this a lot because there are quite a few strike partnerships in the Premier League," he said.
"There are some very good centre forwards.
"As you would expect, we have got a partnership that can rival any other partnership."
United head south to face a Tottenham side on Sunday that is still smarting from their 6-0 hammering at Manchester City last weekend.
As Andre Villas-Boas' men have also had a trip to northern Norway for their Europa League encounter with Tromso, now may be a good time for the Red Devils to catch the north London outfit.
Yet Moyes is wary of reading too much into recent results.
"It can vary," he said. "We know that no matter when you play Tottenham Hotspur, it will always be a hard game.
"The games against Manchester United have been good. It is one of these things, we are both coming off the back of European games as well.
"But we will go down there and try to win the game, as we always do."