The match was paused by referee Anthony Taylor midway through the half, with Semenyo telling the ref that racist abuse had been directed towards him from the crowd.
After a pause, where Taylor spoke to both Iraola and Liverpool boss Arne Slot, the game resumed – the Cherries going on to lose 4-2.
Semenyo, though, scored the two Cherries goals to draw them level with their hosts at 2-2, with both goals brilliant efforts, the second a wonderful solo goal.
The Premier League has confirmed that a full investigation into the incident will be launched.
Asked about the incident, Iraola told the Daily Echo: “I didn't notice live because a lot of people were shouting.
(Image: Peter Byrne/PA Wire) “But straight away, Antoine and the ref both explained the situation to both managers. To be fair, I think from the Liverpool side they have identified this person.
“It's a shame that in the first game of the Premier League, a very good game of football between two teams that are fighting for their side, but playing a really good game.
“We have to start talking about things that probably we considered already from the past. But obviously they are not from the past.
Match report:
“We have to continue reinforcing the messages. And it's a big shame. It's a big shame because the end most of the news will be about this thing. And they have to be about the thing because obviously something that still is a big problem, not just in football, but overall and also in football.
“We should be talking about what a good game it has been. Two teams playing well in the first game of the season. And probably we'll be talking about other things.”
Asked about how Semenyo was doing, both immediately following the incident and after the game, Iraola said: “In the heat of the moment I think Antoine understood the situation.
(Image: Peter Byrne/PA Wire) “He was calm. He continued playing, for sure he has been, the head works in the next minutes. But we asked him, he was fine to continue. He looked composed.
“But it's true that now at the end of the game he was still, for sure he will be, not on purpose, but the head always goes to these things and for sure he's asking why it still is happening today and it's a big shame.”
A Premier League statement said: "Tonight's match between Liverpool Football Club and AFC Bournemouth was temporarily paused during the first half after a report of discriminatory abuse from the crowd, directed at Bournemouth's Antoine Semenyo. This is in line with the Premier League's on-field anti-discrimination protocol.
"The incident at Anfield will now be fully investigated. We offer our full support to the player and both clubs. Racism has no place in our game, or anywhere in society.
"We will continue to work with stakeholders and authorities to ensure our stadiums are an inclusive and welcoming environment for all."