Pearce has named his 18-man squad, leaving out Beckham as expected.
"Form plays a big part and I don't think there is a manager around who picks on sentiment," he said.
"I have to be comfortable when I have made decisions based solely on football grounds alone, nothing else."
Pearce also ruled out any possibility of using Beckham in a coaching capacity, although the British Olympic Association (BOA) has been in touch with the Los Angeles Galaxy midfielder's representatives about a possible Games role.
"We only have seven passes [for backroom staff]. We have no passes for that," added Pearce.
"The players have to be prepared to come through the door on form alone and that happens to be the case with staffing too. They have their role to play."
BOA chef de mission Andy Hunt said it would be "fantastic" to have Beckham involved in some capacity.
He said: "We'd be delighted and honoured to have David Beckham related to Team GB more broadly.
"That would be fantastic. I've made contact with his representatives over the weekend and we'll see how that moves forward."
It had long been anticipated that Beckham would be included as one of the three overage players in the squad following his prominent role in promoting London 2012.
But Pearce instead opted for Craig Bellamy, Ryan Giggs and Micah Richards - three players the England Under-21 manager believes will give Team GB their best chance of winning a medal.
Pearce said he made it clear when he was appointed that he would only pick players based on merit, and would not have taken the job if he was not in full control over squad selection.