Thousands of fans without tickets had already gathered outside the stadium in Basra early in the morning hoping to enter the final between Iraq and Oman, kicking off at 19:00 local time.
When panic broke out, the gates were still closed, says one of AFP's photographers in Basra.
A doctor at Basra General Hospital says according to AP that two people have died and that at least 38 people have been injured.
However, some of the injured have already been discharged from the hospital.
The Men's Gulf Cup is held every two years, with eight participating countries: Iraq, Oman, Kuwait, Saudi Arabia, Qatar, United Arab Emirates, Bahrain and Yemen.
War-torn Iraq has for a long time been stopped from hosting international football matches.
This year, it is the organizer of the Gulf Cup for the first time since 1979.