Unfortunately, those are not cultures that value forgiveness. So vengeance tends to rule their thinking and behavior.
What exactly do you know about "those" cultures, and are you aware that the Middle East is highly diverse in its cultures and, therefore, referring to said cultures as "those" as if they were all similar (unless you didn't mean to imply that, in which case this doesn't apply) is inaccurate?
Not to mention that Iran is ruled by an extremely authoritarian regime, so that regime's actions could hardly be taken as an accurate representation of even that one country's culture and people.
Vengeance rules a lot of countries' decisions on certain issues, so I don't see that issue as unique to any specific region or culture. The country that launched two invasions in the span of less than three years—in which it killed over half a million people—in revenge for an attack that killed 3,000 people certainly wasn't Middle Eastern.