Spain coach Julen Lopetegui labelled the whistles aimed at defender Gerard Pique in Murcia as unfair.
Pique was targeted by some fans at the Estadio Nueva Condomina as Spain played out a 2-2 draw with Colombia in a friendly on Wednesday.
While Lopetegui insisted he was unfazed by the whistles, he believes they are disrespectful to the 88-time international and Barcelona defender.
"It's not good. If someone whistles, they're not being fair to Pique, for everything that he has done for the national team," he said.
"They don't worry me [the whistles]. What concerns me is that we keep improving as a team. There's a fantastic atmosphere."
Lopetegui was pictured having a quiet word with Pique ahead of the Colombia friendly, with reports suggesting it was to discuss his behaviour.
But the 50-year-old coach slammed those reports, saying the conversation was purely about football.
"Every time I speak with a player on the pitch, I talk about football," Lopetegui said.
"Let's not confuse interpretation with invention. You have to have a limit. Inventing a conversation is very ugly."
Alvaro Morata's late equaliser earned Spain their draw against Colombia, who had taken a 2-1 lead as Radamel Falcao became the nation's all-time leading goalscorer.