The Red Devils have already had at least two offers for the 26-year-old midfielder rejected by the Catalan club in recent weeks.
The latest reports have suggested that United are preparing a final bid of around £35m to lure the former Arsenal captain to Old Trafford.
But the Manchester United boss says he is not sure if the Premier League champions will table another offer for the Spain playmaker.
“I couldn’t tell you if there will be another bid,” Moyes said. “Obviously we’ll take stock and make a decision on what we do next.
“But we have a good squad already. You can’t forget about the quality that’s already here.”
Moyes also confirmed that he is confident that United will bring in reinforcements before the transfer window closes.
“Undoubtedly we hope to add to it and I’m quite confident we’ll do that… certainly before the window shuts.”
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