The 28-year-old France international was the subject of a rejected £14million bid from Paris St Germain on Sunday, and the Magpies were bracing themselves for a second approach on Monday afternoon with less than five days of the January transfer window still to run.
Pardew has no desire to sell the former Lille player, who has become a central character in his team, but having lost striker Andy Carroll to Liverpool three years ago, knows a bumper offer could see matters taken out of his hands.
Asked if he was confident Cabaye would remain a Newcastle player after Friday's 11pm deadline passed, he said: "You are talking to someone who lost Andy Carroll with eight hours to go, so am I confident?
"No, I'm not confident, and I don't think any team not in a Champions League position or fighting for a Champions League position could be."
However, if PSG are to get their man, they will have to increase their offer substantially with Newcastle looking for in excess of £20million before they will even consider selling him.
Pardew said: "We know we have got a club interested in Cabaye, a very wealthy club and a powerful club, and we are conscious of that.
"We are doing our best to protect Newcastle."