The Liga club's head coach says he wanted to purchase the Internacional striker in the transfer window, but his salary was a stumbling block.
The forward joined Internacional last summer after a fruitless season with Inter, and the Brazilian side finished ninth in the Brasileiro in 2012.
Jimenez believes the ex-Manchester United front man would have been an excellent fit at the Liga club but financial restraints meant his wage was too huge an obstacle to overcome.
"I asked [president] Agapito [Iglesias] to sign Forlan," Jimenez told Aragon Radio. "He was a good fit, a veteran player who was still a good reinforcement, because he could have guaranteed us 10 goals, by the end of the season.
"It was enough to save us, but he demanded 2 million euros net salary, which we could not afford."
Forlan was key to Uruguay’s success in major international tournaments in the past few years, as his goals helped guide the South American nation to a World Cup semifinal in 2010 and then Copa America success in 2011.
Zaragoza currently sits 16th in La Liga having played 23 matches, just four points clear of the relegation zone.