Iran will face Kuwait on Monday in Group D, while Bahrain take on Afghanistan.
Alireza Rafieipour, Mehdi Karimi, Behrouz Azimi and Saeid Ahmad Abbasi (two goals) were on target for Iran, while Mirza, Saleh Sanjar and Ali Alaraibi scored for Bahrain.
Iran had defeated Afghanistan 3-1 in its first match.
The competition is underway in Bangkok, Thailand, from April 17 to 28.