Ajax and Spurs have settled on a €45m fee, which was agreed last night.
Kieft doesn't understand why so many are upset with the Colombia international defender's behaviour.
He told Ziggo Sports: "Players now have more power than before, even if it sounds so annoying.
"It's very naive of Ajax how they respond now," says Kieft. "You bought a defender with the idea to sell him. They only responded very badly.