The 2010 champions took 54 minutes to break down their opponents at the Kazan Stadium, seeing them join Portugal on four points at the top of Group B.
Carvajal is unhappy with Iran's overly-defensive mindset prior to falling a goal behind, while also hitting out at the Asian opposition's play-acting in La Roja's 1-0 victory.
"The team sits back and that is a tactical strategy that is part of the game," he told reporters. "But the injuries are simulated. This is not football, it is disloyal, but everyone there with their conscience.
"It has been hard for us to open the door. 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."