Despite dominating possession in the Group B opener in Bangkok, Thailand, Abdi’s boys had to wait 28 minutes to get off the mark, when Hesam Nafari headed home a first goal at the event for the country.
Esmaeil Qolizadeh doubled Iran’s lead from the spot four minutes later but Hakim Khan Niazi’s deflected free-kick pulled one back for Afghanistan.
Kasra Taheri scored twice either side of the interval and Qolizadeh netted his second in the 51st minute with Reza Qandipour adding the sixth with one minute left from normal time.
The victory saw Iran go joint-top of the group table alongside South Korea, which also thrashed Qatar 6-1 on Friday.
“The first game in every tournament is always a tough one and we were lucky to score after missing so many chances early on,” Abdi said after the match.
“These players are a bunch of 16-year-olds who often perform with stress or want to do more than they are capable of.
“The big challenge for a footballer at this age is to remain confident and patient, while following the team’s gameplan and philosophy. We stayed patient until we broke the deadlock and goals kept coming for us after that,” added the 56-year-old manager.
“We took our foot off the gas after we had a comfortable lead in the second half as the players’ fitness is also of high priority for us. That’s why we made the substitutions.
“It was important to win the first game as the players will have a better recovery and concentration for the future matches,” Abdi added.
Next for Iran is a game against Qatar on Monday before Abdi’s side squares off against South Korea three days later.
The top two of the four groups will advance to the quarterfinals of the tournament, with the winners of the four last-eight round qualifying for the FIFA U-17 World Cup later this year.