After Callum Wilson's first-half brace for the visitors, the hosts fought back after the break through a Marcus Tavernier penalty and an Enes Unal strike.
Afterwards, Iraola told the Daily Echo: “I think overall I'm not happy with the result.
“Even if we came from a 2-0 scoreline, I think we've been much better than West Ham. I think even in the first half we conceded two goals, but we were not worse than West Ham.
“Now because you’re losing 2-0, they will say, no, the first half is for West Ham. No, the first half, we've been better than West Ham, but we conceded two goals that we shouldn't concede.
“But second half we've been miles better than West Ham and we had so many chances that for us is a bad point. It's a bad point.”
He added, “I think we haven't been as good in the build up, not in the build up like in the final pass in the last third, from the centre backs probably.
“And we've improved a lot in the second half. But to find reasons we haven't won, a lot of reasons.
“But looking at us, we cannot concede two goals today. How the game has gone, not even one, I would say. And our mistakes from our side that we have to accept and it has cost us definitely two points today.”