Referee Mark Halsey missed the knee-high tackle during Wigan's 2-1 victory at the DW Stadium a fortnight ago and McManaman was not punished retrospectively because one of the officials had seen the incident.
Martinez said: "I think we've been going on and on too much about it. I think it was a football incident. We lost Ryo Miyaichi a couple of weeks back and he had to go through surgery and he's out for the season. Those are incidents that happen in the game."
McManaman, 21, was confronted by an angry Newcastle assistant boss John Carver at half-time and figures within football have queued up to condemn the tackle.
It was initially feared Haidara had suffered a serious injury but Newcastle have since confirmed he sustained only bad bruising and soft tissue damage, although no date has yet been set for his return.
Martinez added: "I think we're taking things out of context here. I think the whole incident has been a bit of an argument about the refereeing in the game. It was a challenge with no real intent. It was an unfortunate incident that happens on a football pitch.
"I think we've been talking too much about it and it's a bit unfair on a young man to have to suffer that."
There has been no official apology from Wigan but the two medical departments were in touch until it became clear Haidara was not seriously hurt, while McManaman also contacted the Newcastle player.
The striker has started Wigan's last two games, scoring in the FA Cup quarter-final win over Everton, but may miss Saturday's Barclays Premier League clash with Norwich because of an ankle problem.
The Wigan boss added: "I did have concerns straight away. Anyone would. He's had a very good development at the club. He's been out on loan and I think he's had enough experiences to know how to cope with anything the Premier League is going to throw at him."
- Sports & Recreation