That was considered as a possibility since the aircraft was not produced in large numbers.
So either the aircraft is a completely rebuilt helicopter captured from Iraq, or obtained from another source, nor built it from scratch themselves. The later option is a possibility since the Bell 214ST model was designed and meant to be produced in Iran but because of the Revolution the first flight occured in the US not Iran. Considering the level of cooperation in the project it is quite feasible the blueprints were found in Iran somewhere.
However I do favor the idea of it being captured from Iraq though I have never seen any reports of that particular helicopter coming into Iranian hands but who knows.
Also, the TV3 engine doesn't necessarily mean the attack helicopter would be large. Remember, the Mi-28 uses those engines and its no bigger than the AH-64.