Luis Suarez scored twice either side of a Raphael Varane own goal as Barca claimed a 3-0 win at the Santiago Bernabeu and a 4-1 aggregate victory.
The defeat means the Catalans are into a sixth consecutive Copa final, having won the trophy four years in a row, while their treble hopes for 2018-19 remain alive.
However, Solari does not think their defeat to Ernesto Valverde's side should be considered a disastrous result.
"Football is a forceful game," he said. "We applied ourselves well, with energy, but we weren't decisive.
"We have been beaten with honour, but we're sad because this is a tough blow for us to take. It isn't a failure because it was a semi-final and we won't be able to play in the final, so we will have to try again.
"We had chances in the first half but also in the second too when the score was 1-0. I never thought we lost control of the game, but they scored with their first shot of the game and then got another with an own goal.
"We didn't score when we had our chances and there's nothing more to add about it."
Vinicius Junior missed two good chances in the first half before Suarez broke the deadlock, but Solari is confident the 18-year-old will improve his finishing with time.
"It's something that can improve with the passage of time, and with maturity, but especially in training," he said. "There isn't much time between matches, but he can also improve in training."
Madrid host Barca once more on Saturday in La Liga.