That offer falls short of the 28-year-old's £26 million release clause by some distance, while he is contracted at the Mestalla until 2017.
However, Spurs are hoping to take advantage of the La Liga outfit's financial difficulties and hope the reduced fee will be enough to persuade them into doing business.
Soldado was an unused substitute during Spain's 3-0 defeat to Brazil in the Confederations Cup Final on Sunday night, though he has eleven senior caps to his name at international level, scoring in six of them, and is expected to put pressure of Fernando Torres and David Villa for starting places at next summer's World Cup.
Spurs boss Andre Villas-Boas is in the market for two new strikers this summer and has offered Barcelona £10 million for Villa, 31.
However, Spain's all-time leading goal-scorer has also been linked with a move to Arsenal and if the Lilywhites fail with their pursuits, they do have other irons in the fire.
Brazil marksman Leandro Damiao of Internacional is also on their radar as a fall-back option, while Loic Remy, another Arsenal target, is also on their wish list this summer.