The move followed criticism from prominent figures in the game.
The website at first explained how fans registering for a 2019 access pass could win a “grand prize” to see the 2019 men’s semi-finals.
Runners-up could win tickets to the women’s semi-finals.
Ms Murray said the prize sounded “great, until you get to the second paragraph”, which read: “And if you don’t win the grand prize, don’t worry, there’s more. You will have the chance to win 2019 women’s semi-finals tickets.”
The wording on the website has been changed ahead of the tournament, which begins on 26 August, but Navratilova expressed her “disappointment” in a reply to Ms Murray, as social media users shared their views.
“What a poor message to send out, women being the consolation prize,” posted another Twitter user.
While another tweet read: “Big fail @usopen. Women’s sport is not second-class, the runners-up prize or in anyway inferior. Really disappointed this is your attitude. Change it, it’s soooo out of date.”
In a seperate post, one Twitter user suggested other ways of describing the prize could also be problematic. “The alternative is men being the consolation prize, and that’s as insulting as what they’ve put above. They literally can’t win.”
In a statement the United States Tennis Association, which runs the US Open, apologised for the language it had used in its original description. “While describing the prizes in the Ultimate US Open Experience, the language used inadvertently compared the men’s and women’s semi-finals unfavourably.
“The US Open is proud of its long tradition of gender equity and we sincerely apologise for not adequately describing the differences in the prize packages,” it said.
The US Open was the first Grand Slam tournament to offer equal prize money to men and women, in 1973. Wimbledon was the last to do so, in 2007.