"Vietnam are the strongest team in this tournament," he told VnExpress on Monday night.
"They are the champions of the previous tournament and are also playing really well this year.
"Thailand will work hard to find a suitable strategy if we face Vietnam. Let's see what happens on the field."
Sritaro led the Thailand U22 team to the final of the SEA Games football event in May, where they drew 2-2 with Indonesia after 90 minutes and lost 2-5 in extra time.
The match saw brawls break out between the two teams.
Sritaro then took over the U23 team for the AFF U23 Championship.
Last year Thailand lost 0-1 to Vietnam in the final.
This year they are in outstanding form, scoring consecutive wins over Myanmar, Brunei and Cambodia, scoring eight goals and conceding one, and topping group A to reach the last four.
They will take on the best second-placed team in the three groups. It can be Indonesia, or Vietnam if the team lose to Philippines by three goals or less in the last match in group C on Tuesday.
Sritaro said: "At the moment we don't know whether we will meet Indonesia or Vietnam. We cannot say which opponent is harder to deal with. But in football, if you want to win the title, you must defeat the strongest opponent."
Sritaro, who was coach of the U19 Thai team that lost to Vietnam in 2019, said most of that Vietnamese team is playing for the current U23 team and so he is familiar with them.
Asked to name the most impressive Vietnamese player, he said: "There are too many; I can't remember the names."
He and his assistants are expected to go to Rayong Stadium to watch the match between Vietnam and the Philippines on Tuesday.
In their opening match in group C, Vietnam beat Laos 4-1. They only need a draw to enter the semifinals as the winner of group C and face the winner of group B, Malaysia.
If they lose by three goals or less, they will still advance as the best second-placed team, but will take on Thailand instead.
The 2023 AFF U23 Championship is being played in Rayong from Aug. 17 to 26.