The Londoners had asked United to pay £30m before accusing them of unsettling their star player.
Spurs' move is sure to further infuriate Old Trafford boss Alex Ferguson following the war of words that kicked off between the two clubs last week over Berbatov.
Fergie hit back at Tottenham by branding them "hypocrites".
United have made a £20m take-it-or-leave-it bid for Berba, who wants to quit White Hart Lane.
But Barcelona boss Pep Guardiola and Milan chief Carlo Ancelotti are keen admirers of the ex-Bayer Leverkusen star.