"We cannot sign permanently. We can only loan players," Emery told a news conference ahead of Saturday's league trip to West Ham United.
The Spaniard pointed out the difficulties in recruiting players in the January transfer window but said the club were keeping their eyes open.
"I know the club is working on possibilities of which players can help us with big performances like we need now," Emery added.
"If we can find one player who can help us like we need, with the quality and a different player for getting in our squad, we are going to do it."
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Arsenal's transfer strategy in recent seasons has seen players run down their contract and leave for free, the latest being midfielder Aaron Ramsey who is set to join Juventus in the close season after failing to agree a new deal.
"I respect his decision a lot. My last conversation with him is very important," Emery said.
"We both spoke about the situation with respect from him and from us. His response has been very good in training and matches with good performances.
"I want his behaviour and his focus to be on West Ham on Saturday."
(Reporting by Rohith Nair in Bengaluru)
