Madrid lost the first leg 2-0 and went behind to a Pedro goal nine minutes into the second half at the Nou Camp, before Marcelo gave Jose Mourinho's men hope of a recovery.

That never came as Barca cruised to their third Champions League final in six years with a 3-1 aggregate win.

But Madrid have pointed to an incident early in the second half, when Gonzalo Higuain netted only to see his effort chalked off as play was stopped only moments earlier.

Cristiano Ronaldo accidentally tripped up Javier Mascherano in the lead-up play, although the Portugal international appeared to have himself been tripped by a home defender to initiate the contact.

"(Jose) Mourinho was right," Karanka said.

"He said that it would be impossible for us to go through. Tonight proved that it was impossible and 100 million people saw it - there is nothing more to add."

Madrid goalkeeper Iker Casillas, who kept his side in the game with a string of fine saves in the first half, was also frustrated at the decision to disallow Higuain's strike.

"It has happened again - just like always," he said after the game.

"Playing 11 against 11 we have shown we can compete without complexes and it takes me back to the first game; if we had finished 0-0 (the score before Pepe was sent off), tonight's 1-1 would have taken us through to the final."

Mourinho, like Pepe, was banned following his own red card in last Wednesday's ill-tempered first leg and, unable to communicate with the Madrid bench during the game, the Portuguese chose to stay away from the stadium.

"We couldn't have any communication with him, but we talked about the game beforehand and the changes we could make," Karanka said.

"He wasn't on the bench and couldn't be in the ground, but we spoke after the game and he congratulated the team because we played well."

The match brought the sides' series of four Clasico matches to an end, with Barca getting the better of their biggest rivals overall.

The first meeting, 18 days ago, ended in a 1-1 draw at the Bernabeu in the Primera Division, while Madrid came out on top to win the Copa del Rey four days later.

And although Barca sealed passage to the Champions League final after dominating over the last two games, Karanka believes his side can take plenty of positives from the four matches.

"We finished 11 against 11, almost like in the final in Valencia (when Angel di Maria was dismissed right before the end of extra time), and we showed we can be competitive," he said.

"Of the four games, we have drawn two and won another. We can be proud of how we have done and we fought until the end."