The 23-year-old wing-back took to social media on Sunday to address his heated exchange with Quique Sánchez Flores, a moment that had dominated conversation after Alavés' 3-0 victory over Getafe at Mendizorroza.
Pérez, formerly of Huesca, was substituted in the 65th minute for Youssef and reacted furiously, punching the bench several times in frustration at being withdrawn while the scoreline still stood goalless. Sánchez Flores turned to remonstrate with his player immediately, and television cameras caught the pair exchanging heated words before Moussa Diarra stepped in to defuse the situation, according to Cope.
Writing on his personal account, Pérez said: "I also wanted to take the opportunity to apologise publicly to my teammates, coaching staff and supporters, as I already did in private.
"It was a moment of frustration with myself in which I shouldn't have acted that way, given that the situation from the outside can be misunderstood.
"I'm a person, I make mistakes, and I also know how to admit them. Thanks to my teammates and the coaching staff, it's all in the past now."
Sánchez Flores had already moved to play down the incident in his post-match press conference, telling reporters with a smile that summed up his mood: "Today I love him more than yesterday."
The Alavés head coach reportedly felt the outburst was disrespectful not only to his own decision but to Youssef, the player who replaced Pérez, though he chose not to dwell on the matter publicly once the dust had settled.
Sánchez Flores took charge at Mendizorroza this summer on a contract running to 2028, and has generally been protective of squad unity as he builds his side for the season ahead.
The clash came on an afternoon otherwise dominated by Mariano Díaz, whose goal and celebration for Alavés provided the standout image of the club's first win of the campaign. Getafe played the entire second half with ten men after Kiko Femenía's dismissal, further easing Alavés' passage to three points.
Pérez was among the more prominent Alavés players in the first half before his withdrawal, with his frustration stemming from the belief he still had more to give with the game still goalless at that point. The confrontation briefly threatened to overshadow what was otherwise a perfect opening weekend for the Basque club, who could hardly have asked for a better start under their new head coach.
With tempers now cooled and the apology delivered both privately and publicly, both player and club appear keen to move past the incident heading into Alavés' next fixture, having opened the LaLiga 26/27 campaign with the perfect result.