Crouch was shown a second yellow in the 15th minute as Spurs went on to lose 4-0 at the Santiago Bernabeu but Jenas, who was called in as a late starter for the ill Aaron Lennon, said referee Felix Brych may have been wrong.
"I think the referee was a little bit rash," Jenas said.
"Maybe it was inexperience on his part more than anything.
"At some point you have a word, you just talk to the player, rather than dishing out cards every two minutes."
Jenas added the Crouch had given his apologies to the playing group but said the match may have been a different story if the London club had 11 players for 90 minutes.
"He was disappointed, as any professional would be," Jenas added.
"He knew what he did probably wasn't a sensible decision, but everybody was so fired up for the game and these things can happen.
"As soon as it happened my heart sank. We were up against Real Madrid with 10 men for 75 minutes. We stood up to them for a bit but it wasn't enough."