Police made the apology after some participants at the training course expressed their outrage.
While they had been warned they would see images of women in underwear, they were expecting a post-accident scenario, El Público reported on Tuesday.
But what they saw instead was a 'highly erotic' YouTube video with a content warning featuring two lingerie-clad models demonstrating cardiopulmonary resuscitation, or CPR.
Another video about the Heimlich manoeuvre — which is designed to prevent people from choking — contained images of a man and a woman in very close contact.
After the training session at police headquarters in the town of Jaca, a number of participants demanded an apology.
On Tuesday, this was forthcoming. "We apologize for showing these videos, which were inappropriate," official sources were quoted as saying by local daily Heraldo de Aragón.
"The videos won't be used again," those sources added.