Souness slammed United's handling of the situation, and revealed what he would do with Ronaldo.
He told talkSPORT: "I would have tried to have nipped it in the bud before now. I'd have got in front of him as soon as possible.
"We all know how the game works, his people and Jorge Mendes would have been speaking to clubs and asking could they afford him.
"I don't believe that he's gone out on a limb and said that he wants to leave without having something going on in the background.
"It seems that there is still somebody out there for him, but they're not willing to show their hand."
Souness added: "From the United view, you try keep him. There's an argument to say that he's the greatest player ever to kick a football, his stats and his longevity would suggest that.
"I would keep him. He doesn't get goals against the big teams, the game passes him by a bit and he plays the width of the box, but he does get goals.
"We all know how important goals are to the cause as you can be not playing very well, but if you've got a goal-getter then it makes you look like a very different team.
"Goals are everything and it's the hardest job in football. I'd go out of my way to keep him."