The north Londoners have sent technical director Franco Baldini to Spain to negotiate a deal for the 28-year-old, who scored 30 goals in all competitions last term.
Valencia president Amadeo Salvo has insisted Soldado will only leave the Mestalla if a club matches his £25 million buy-out clause, with Villas-Boas stressing that no deal has yet been agreed with the Liga outfit.
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"It's not a lie to anybody that we've been looking for a striker to strengthen our squad and to have more strength in depth.
"Roberto is one of the players we have been following and his career speaks for itself. He's a great striker.
"But there isn't a deal being struck at the moment, it's just interest and conversations."
With just Jermain Defoe and Emmanuel Adebayor the only first-team strikers at Villas-Boas' disposal, the Portuguese is keen to bolster his attacking options and have turned his attentions to Soldado after the club refused to meet Aston Villa's £25m asking price for Christian Benteke.