This is not football - Carvajal criticises Iran tactics
Diego Costa's fortunate goal settled a tight contest in Kazan, moving Spain level on points with Portugal at the top of Group B.
Iran had a goal disallowed following a VAR review, while Mehdi Taremi was among those to miss chances for Carlos Queiroz's side.
Real Madrid right-back Carvajal, though, felt Iran's defensive tactics were over-the-top, while hitting out at what he perceived to be play-acting.
"The team sits back and that is a tactical strategy that is part of the game," Carvajal said.
"But the injuries are simulated.
"This is not football, it is disloyal, but everyone there with their conscience."
All to play for in Group B for #POR #ESP and #IRN in the final round of fixtures... #WorldCup pic.twitter.com/75h32KvqE6— FIFA World Cup (@FIFAWorldCup) June 20, 2018
Carjaval is now hoping future opponents at Russia 2018, starting with Morocco in their Group B closer, are more ambitious in their play.
"It has been hard for us to open the door," Carvajal added. "But we kept the clean sheet despite the chances they have had - they are three very important points.
"We are a team that plays direct, open and I hope we do not have rivals that put many players in their area."