He remained committed to chasing major victories on the PGA Tour.
The Northern Irishman, competing at this week's PGA Tour event in Charlotte, North Carolina, likened the proposed rival circuit to European soccer's breakaway Super League project that spectacularly collapsed last week before it could get off the ground.
"You go back to what happened last week in Europe with the European Super League in football," said McIlroy, who has nearly $US55 million in career earnings on the PGA Tour.
"People can see it for what it is, which is a money grab."
McIlroy was speaking a day after a report in Britain's Daily Telegraph detailed a renewed Saudi Arabian-led plan to create a breakaway rival circuit that promises lavish payouts to those who agreed to join.
According to The Telegraph, players have been offered between $US30 million-$US100 million to take part in SGL, but the PGA Tour has threatened members with instant suspension and a lifetime ban if they join the breakaway.
McIlroy, who said he was first approached by the SGL in 2014 when it was known as the Premier Golf League, has spoken out against it before.
"I think the top players in the game, I'm just speaking my own personal beliefs, like I'm playing this game to try to cement my place in history and my legacy and to win major championships," said McIlroy.
"Golf has been very good to me obviously over the years by playing in Europe starting off, coming over to the PGA Tour and playing here. I honestly don't think there's a better structure in place in golf, and I don't think there will be."
World number two Justin Thomas said that while other golfers at different stages in their careers may feel differently, he has no desire to give up his pursuit of major victories on the PGA Tour.
"For me, I personally am about being No1 in the world and winning as many majors as I can and winning as many tournaments as I can and doing historical things on the PGA Tour," Thomas said at Quail Hollow Club, where play begins on Thursday.
"If I was to go do that, then all those things go down the drain and I can't do that."
