Iraq conceded two goals in stoppage time in a surprise 3-2 defeat to lower-ranked Jordan in Doha.
Tempers flared among some Iraqi reporters in the post-game press conference, who pointed and shouted angrily at Casas, and approached him at the front of the room before being ushered out by security.
"It pains me what happened," the 50-year-old Spaniard, who has been Iraq coach since November 2022, said of the chaotic scenes.
Iraq's football association released a statement in which it expressed its "great dismay" at the "scene that was more painful than the undeserved exit of our team".
"We denounce the blatant and abhorrent behavior that occurred against the coach," it said, vowing "not to deal with these media personnel who seek to cause chaos".
Casas was himself angered in Sunday's pre-match press conference by a question about interviews he has done with Spanish media during the Asian Cup.
Some journalists from Iraq, the country that won the Asian title in 2007, believe the interviews distracted him from his work and were partly to blame for the defeat.
Casas rubbished that notion, pointing out that his team had won all three of their group games, including beating pre-tournament favorites Japan 2-1.
"Concerning my future, I'm calm and our goal is to qualify for the 2026 World Cup," Casas, a former assistant coach to Luis Enrique at Spain's national side, said after the Jordan loss.
"Anything might happen and I'm very calm."