The Wynn cash-and-shares proposal sent Crown shares soaring by a fifth in Sydney on Tuesday, increasing the value of Mr Packer's stake by A$700m.
Crown had earlier confirmed that it was in acquisition talks with Wynn.
"Following the premature disclosure of preliminary discussions, Wynn Resorts has terminated all discussions with Crown Resorts concerning any transaction", the firm said in a statement.
That offer would have valued Crown at around $10billion.
Unlike its competitors who already have footholds elsewhere in Asia - from Las Vegas Sands Corp.'s Singapore resort to Melco Resorts & Entertainment Ltd.'s City of Dreams in Manila - Wynn is now confined to Macau, where expansion is approaching its limit.
Wynn's backtracking illustrates how media leaks of deal talks can test the resolve of potential acquirers.
It comes as fears about Crown Resorts' new casino development in Sydney weigh on the company's share price, while a slowdown in spending by VIP gamblers at its Melbourne and Perth casinos weighs on the company's turnover. In this case, Wynn's inexperience with pursuing big deals also likely played a factor, some analysts added.
The talks had been going on for some months and involved a previous offer, The Australian newspaper reported.More news: National Hockey League head coach gives interesting take on Bruins vs. Leafs playoff series
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A few hours after that filing, the US firm announced it was ending talks with Crown Resorts.
Wynn's interest in Melbourne-based Crown, which is nearly exclusively focused on its domestic market where big-spending VIP gamblers have become more elusive, seems unusual, but the Las Vegas-based empire is desperately seeking to shore up its presence among Asian bettors.
Crown's value has fallen 20% since mid-2018 as profits have fallen short of expectations.
Wynn has properties in the United States and Macau, but over the past year it has ramped up promotion of a resort in Japan, a market seen as the next potential goldmine to Macau and a former expansion target for Crown. Its founder, Steve Wynn, resigned as chairman and chief executive in February 2018 after claims of sexual misconduct, and has sold his stake in the company.
A court jailed 16 of the defendants, including three Australian citizens, for nine-to-10 months, with the remaining three released after a month in detention.
The company has had some prior dealings with Wynn, having sold the company a 34.6-hectare parcel of land adjacent to Wynn Las Vegas on the Las Vegas Strip in December 2017 for AU$300 million.
A spokesman for Consolidated Press Holdings, Packer's company which holds his Crown shares, was also not immediately available for comment.