Ipswich lost 1-0 via a penalty won by Jota Silva and converted by Chris Wood.
“I’ve not seen it back closely, to be honest, in terms of the decision,” said McKenna. “Of course, it was a big moment in the game.
“It was a really tight game, it felt like the first goal in the game was going to be decisive.
“We had our opportunities to get it in the first half, we didn’t manage to. We felt coming out in the second half, we had it in us to step up to another level and we gave away a penalty really early in the half, and it ended up deciding the game.
“I’ve not had the angles of the decision back, but I think we have to own it and we have to look at it and say that you can’t lunge in from behind in the penalty area.
“We had the box well covered, we had plenty of people in the frame of the goal and it’s not a particularly threatening situation.
“I think away from home more than at home, we shouldn’t give the referee the possibility to make a decision there and it ends up in the decisive moment in the game.”
McKenna added: “We competed pretty well on that, to be fair. We had a threat on set plays ourselves, we had a lot of set plays.
“It wasn’t a particularly high quality game, I didn’t think, there wasn’t a lot of flow to it. Both teams felt like they were a threat when they got to the other team’s box. We certainly felt like we were a big threat every ball we got, especially out to the right-hand side in the first half.
“But it wasn’t a game of great flow, neither team created an awful lot from open play and set pieces and being really, really disciplined can make the difference, and we didn’t manage to score one of the set plays that we got and we’ve given away a pretty soft goal from our point of view.”