Garcia questioned the decision to rule out Pedri's second-half equaliser.
"We're p***ed off with the result," Garcia told Movistar. "We managed the game well at the start, getting wide into one on one situations.
"The goal hurts, just before the break when things seemed in control. In the second half, it was just them defending and us trying to attack...
"The goal they disallow... I don't know exactly. It has been explained to us that if the player that touches the ball with his hand, scores, the goal doesn't count. But if it touches another player's hand involuntarily, it's a goal. And I think it hits Ansu's (hand) off a touch from Onana."
"The Dumfries handball... I don't know. But we can't change anything now," Garcia added.