Barcelona appealed for a penalty after Atletico goalkeeper Juan Musso appeared to have put the ball back into play from a goal kick before defender Marc Pubill handled it inside the six-yard area to retake it.
Referee Istvan Kovacs waved play on, and the VAR team did not summon him to the monitor.
Barcelona launched an official complaint on Thursday, but UEFA's Control, Ethics and Disciplinary Body deemed the complaint to be inadmissible.
"Following the UEFA Champions League quarter-final first leg played on Wednesday, 8 April 2026, between FC Barcelona and Atlético de Madrid, FC Barcelona filed a protest relating to a referee decision. On 13 April 2026, the UEFA Control Ethics and Disciplinary Body declared the protest to be inadmissible," UEFA said in a statement.
Barcelona and Atletico meet in the second leg later on Tuesday.