The 28-year-old forward, who scored 74 goals in 264 appearances during two seperate spells with the Iron, was linked with a return to Glanford Park last week.
However, Hayes refuted the rumours via social networking site Twitter, saying: "Out of respect to the Scunny fans, I won't be coming back to the club."
Knill told the club's official website: "We would be stupid if we weren't looking. If you see a player of Paul Hayes' quality available then you should look. He is another one like David Mirfin who has great links with the club. But that's as far as it's got.
"We heard he was available, but it seems not so at the moment. We're not going to pursue it. He's on quite a big wage at Charlton, but if he becomes available then we'll see what we can do.
"It is difficult to find the sort of striker we like because clubs aren't letting any out yet."