Six Barclays Premier League clubs - Arsenal, Aston Villa, Chelsea, Liverpool, Manchester City and Tottenham, are involved in the European tournament along with teams from 11 other countries.
United's Academy manager believes the existing format would not benefit the youngsters making their way through the ranks at Old Trafford.
“The NextGen Series just doesn’t fit in with what we’re doing at present,” McClair told ManUtd.com. “The whole thing just doesn’t fit in.
"If we’re looking at that age group, I think it’s the Under-19s with a few under-aged players but Barcelona were playing all their kids so they had a really young team.
"There is more benefit for our Reserves playing against Wigan Reserves for example as it’s better they play against men and experienced players rather than if they are up against 16 or 17-year-olds, irrespective of what the skill level is.
"It may be great for Barcelona and more beneficial to them but not to us. At present, it just doesn’t fit."