Keane made his comments ahead of England's friendly against New Zealand in Tampa as part of his punditry role, and was unsympathetic toward the centre-back who was passed over in favour of Dan Burn (Newcastle United) and Jarell Quansah (Bayer Leverkusen).
"Every time we do an England game, we speak a lot about players who have been left out or in terms of the squad are left out of the starting XI. But I think if you can't get into a squad of 26, that's on you. That is on the player — you've not done enough to convince that manager."
He expanded his argument to cover the wider pattern of England selection controversies.
"There will always be uproar with England for players that are left out if they play for certain clubs, but that's on you. If you can't make a squad of 26, that's on you — don't blame anyone else."
Maguire, 33, would likely have been included in Tuchel's extended 55-man provisional list but missed out on the final cut.
He has had a more consistent season at Manchester United under Michael Carrick than in previous years but was not deemed necessary given the alternatives available. Burn, 32, was selected primarily for his aerial threat and set-piece ability, while Quansah, 22, offers the youth and developmental profile that fits Tuchel's longer-term approach.
England face New Zealand on Saturday before opening their World Cup campaign against Nigeria on June 16.