The A-League club have renewed their interest after failing to sign the 33-year-old striker this summer.
"It was a 50-50 thing," he told BBC Scotland. "The club was considering it, I was considering it and, in the end, it didn't come to any fruition.
"Obviously it was something I wanted to explore. The club weren't as keen."
The former Australia international is in his second season of a second spell at Fir Park and signed a new one-year contract in the summer.
But the club managed by former Crystal Palace defender Tony Popovic had hoped to take the former Celtic and Middlesbrough striker back to his homeland for the first time since he left Cranbourne Comets for Southampton in 2000.
Asked if the offer was still alive, McDonald said: "It may well be, but that's not in my hands at all. That would be up to other people to discuss it.
"I haven't heard anything else from representatives or anything else that the deal is still there.
"As far as I'm aware, that club hasn't signed anyone else, so if Motherwell were to change their mind - but that's not happening.
"We are where we are and we resume where we are."
McDonald started on the bench for Motherwell's Scottish Cup defeat by Rangers on 21 January, with manager Mark McGhee later explaining that the striker's "head was not in the right place" because of the transfer approach.
"I offered to play, but we had a conversation and we felt I hadn't trained all week leading up and there was a heavy amount of preparation put into that cup game itself in terms of shape and starting XI," said the striker, who stressed that "the manager and the club have been fantastic to me".
"I agreed it wasn't right for me to step in on Friday and basically call the shots - I'm back in the team.
"That wouldn't be fair on the rest of the squad who had worked really hard during the week as well for me to go and take one of their places and the manager agreed on that.
"Of course, the offer was tempting and that's why it dragged on that whole week."
McDonald returned to the starting line-up for the weekend Premiership loss to Rangers and was sent off after 27 minutes for a foul on Kenny Miller and Well have launched an appeal against the red card.
Western Sydney lie eighth in the 10-team A-League.
Scott McDonald has admitted he was "tempted" by an offer from Western Sydney Wanderers but that Motherwell rejected their latest approach.