The Hammers may be left with few attacking options ahead of their match this weekend, which could see a determined approach for Tottenham's Adebayor.
Sky say that a season-long loan, with a mooted £11.5 million fee to make the switch permanent, was in the offing but that the East Londoners will now have to look elsewhere for much-needed options up front.
Zaza only signed for Juventus this summer after an impressive two-year spell with Sassuolo, but the 24-year-old is now a goalscoring Italy international and would have been a big help for Slaven Bilic.
It is a huge blow for the Hammers, who must have been hoping that they would be able to get in attacking reinforcements before the weekend given their dire straits in that department.
Last season's top scorer Diafra Sakho was arrested this week before being released on bail, though he is already out injured alongside Enner Valencia, Andy Carroll and Mauro Zarate in the treatment room.
That would normally leave just Modibo Maiga as an attacking option, but even the Malian's future is uncertain after Saudi club Al Nassr announced earlier this week on Twitter that they had signed the 27-year-old, something the Hammers haven't confirmed.
As things stand, youngster Elliot Lee may be one of the only options for the club for the difficult trip to Anfield on Saturday.
The news could see the Hammers double their attempts to bring Tottenham forward Emmanuel Adebayor to Upton Park, with the Mirror reporting this week that the club were eager to recruit at least one from the Togo international and Zaza ahead of the game with Liverpool.