Amir Hossein Sedaghat top scored Iran with 15 points, while Acosta Wilson led Argentina with 18 points.
Iran, who had started the competition with 3-2 loss against Belgium, will play Morocco in Pool C on Saturday.
The 2021 FIVB Volleyball Men's U-21 World Championship, contested by the men's national teams under the age of 21 of the members of the FIVB, is being held in Italy and Bulgaria from 23 September to 3 October 2021.
Iran is the competition’s defending champion.