The first half ended after one extra minute, with a goal scored by forward Sardar Azmoun of Iran in the 37th minute.
In the third minute, Iran performed a free kick but failed to get past Vietnam's defence.
Goalkeeper Dang Van Lam got down and successfully grabbed the ball from Iran's first attack in the seventh minute.
Three minutes later, Iran took a corner, but Lam excellently got the ball safely in his hands. In the 16th minute, he got his foot out and saved a shot from an Iran attacker.
Iran's forward Mehdi Taremi received a yellow card for fouling Doan Van Hau in the 18th minute.
Que Ngoc Hai blocked a shot and was in pain for few seconds in the 23rd minute.
In the 25th minute, Lam again saved a dangerous shot from Iran.
The first minutes of the second half saw the replacement from Vietnam, with Phan Van Duc subbed out for Nguyen Van Toan.
In the 52nd minute, a tap-in from sub-in Toan gave Vietnam the best chance to score since the beginning of the game, but Nguyen Cong Phuong could not beat the Iran goalkeeper.
Ngan Van Dai, in his very first appearance in the Asian Cup, replaced Pham Duc Huy in the 58th minute.
Vietnam showed a defence mistake and Sardar Azmoun scored the double with a simple finish in the 69th minute.
In the 78th minute, Nguyen Quang Hai took a free kick after Iran received a yellow card for a foul. But the shot was saved by Iran's goalkeeper.
Sardar Azmoun, who scored two in the match, was replaced by Karim Ansarifard in the 77th minute.
Midfielder Nguyen Trong Hoang was subbed out for forward Nguyen Tien Linh in the 88th minute.
Midfielder Do Duy Manh received a yellow card, his second in the tournament, meaning he will not be present in Vietnam's next game against Yemen.
The match concluded with a 0-2 score in favour of Iran.
This is Vietnam’s second loss in the group stage. The team was beaten 3-2 by Iraq in their first match of Group D which took place in Zayed Sport City Stadium in Abu Dhabi, the United Arab Emirates, on January 8.
The Vietnamese squad will wrap up their group stage journey with a match against Yemen on January 16.