This is according to Spanish newspaper Marca, who profiled the 22-year-old England international ahead of Wednesday’s Audi Cup semi-final between Spurs and Real Madrid.
Marca do not disclose how much United offered - but they state that the bid was not enough to tempt Spurs into selling the England international.
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Manchester United are on the hunt for a new striker after offloading both Robin van Persie and Radamel Falcao this summer.
Wayne Rooney, Javier Hernandez and James Wilson are the only recognised strikers at Louis van Gaal’s disposal with just four days to go before the 2015-16 Premier League campaign gets underway.
Tottenham have no desire to sell Kane
A host of high-profile names have been linked with the Red Devils over recent months - including Kane, who scored a magnificent 31 goals in 51 appearances for Tottenham last season.
Spurs have no desire to sell the fan favourite, who grew up supporting the north London club, acutely aware of the impossible task replacing him would prove to be with less than a month to go before the transfer window closes.
Daniel Levy would want a ridiculous fee
Tottenham chairman Daniel Levy is a notoriously tough negotiator and, in all probability, wouldn’t consider any bids below the £50 million-mark.
Considering Spurs received £86 million - a world-record fee - for Gareth Bale from Real Madrid two summers ago, Levy could be forgiven if he valued Kane to be worth a similar amount of money.
Kane can become world class
Kane, at the age of 21, scored five more goals last season than Bale managed in his superb final campaign with Spurs.
Of course, the two stars play in different positions - Bale on the wing and Kane as a centre-forward - but Tottenham have a potential world-class player on their hands and would be mad to sell, regardless of the size of the offer.
One suspects if Levy had the opportunity to rewind the clock and either sell Bale for £86 million or keep him at White Hart Lane, he’d probably opt for the second option.
The difference, though, is that Bale wanted to join Real Madrid - whereas Kane is happy to be playing regularly at Tottenham.
United are wasting their own time
That Manchester United are keen to sign Kane comes as little surprise - this isn’t the first time this summer the Red Devils have been linked with the striker.
But given the fact Tottenham have no desire to sell Kane, United are probably wasting their time.
Manchester United fans: would Harry Kane be the dream striker signing for the Red Devils? Have your say by leaving a comment in the box below!