Unai Emery says Arsenal "cannot" sign players in the January transfer window.
Arsenal are fifth in the Premier League, three points outside the top four, as they seek a Champions League return in Emery's first season in charge.
But the Gunners head coach confirmed in a news conference on Thursday he will not be given funds to add to his squad this month.
Arsenal have been linked with a move for Sevilla midfielder Ever Banega during the window, as well as defensive reinforcements.
However, Emery said the club will only be looking to add players to the squad on a loan basis, with no permanent deals being pursued.
"We cannot sign permanently," he added. "We can only loan players. Only loan players."
Of the link to Banega, former Sevilla boss Emery added: "I know this player and he's a very good player. I cannot tell you more."
Emery was also asked about rumours Arsenal are interested in Denis Suarez, with the midfielder on the fringes at Barcelona.
The Spaniard, though, reiterated Arsenal are not in the market to make permanent transfers during the January transfer window.
"I don't know his situation now," Emery said. "We can only sign players later on.
"I know the club is working on possibilities of which players can help us with big performances like we need now."
Arsenal travel to West Ham on Saturday before hosting Chelsea, the Blues occupying fourth place in the table, in a Premier League London derby next weekend.