The tournament director Lawrence Robertson and team tried to offer Williams the star wildcard into the event but the 23-time grand slam champion on Thursday confirmed she would not be playing; leaving her comeback plans a mystery.
The American tennis star had had a baby girl about four months ago and hasn't played competitive tennis since winning the Australia Open 2017 during which she was pregnant.
"She's taken a decision that she wants to focus fully on her defence of the Australian Open and we've got to respect that," Sydney Morning Herald quoted Robertson, as saying.
He added, "The likelihood is she'll probably go and hit some balls somewhere, most likely in Melbourne. There are a couple of exhibition events down there that she may choose to play in."