The Portuguese side are at Old Trafford on Tuesday for their third Group H game, and Peseiro admits that his side lack the quality that the Red Devils have.
"They're one of the best teams in the world and don't tend to suffer much when they make changes, so it'll be very tough whoever they put out," he said.
"We've got good players and a good team too, so we're going to be trying to win. But if we can't win then a draw is a good result too. We'll need to defend well, try and keep hold of the ball and keep believing we are capable of winning.
"Of course, we don't have the same resources as United, but I have complete faith in the players I've got. It doesn't do the coach or players any good at all if you start thinking any other way."
Braga are currently third in the group with three points from two matches, three points behind leaders United.