"Of course, I have asked for signings," the former Sevilla boss said at his first news conference since his appointment on Saturday to replace the sacked Javier Aguirre.
"There are gaps in the team," Jimenez said, adding that he was aware of the economic woes of the heavily-indebted Aragonese club, who are one of several top-flight sides in administration.
"We need a second goalkeeper, defenders because we are letting in a lot of goals, too many of those from set pieces, something on the creative side and the odd forward," he said.
"I am excited about this new task of getting Real Zaragoza off the bottom, which demands that we all pull in the same direction."
Former Mexico boss Aguirre was appointed in November 2010 and helped Zaragoza avoid relegation last season.
After 16 of 38 matches this term they are five points adrift of the safety zone having picked up just 10 points and the board decided on Thursday "an urgent change of course" was needed.
Jimenez, 47, coached Sevilla from 2007-10 and also played for the Andalusian side.
He was sacked by Sevilla in March 2010 and moved to Greece, where he led AEK Athens to third place in the Super League and victory in the Greek Cup.
