Campbell is currently a free agent after his sensational exit from Notts County, where he decided to walk out on a five-year-contract following his debut for the League two outfit.
But Redknapp admitted he can understand the difficulties that faced Campbell after a career at the highest level.
"Obviously they are a forward-thinking club but it is difficult when you have been a top player and you suddenly drop down all those divisions," he said.
"Obviously he has looked at it and thought 'what am I doing here' but to be fair to him, he's walked away from a big contract so money was not the big factor for him."
Many have tipped Redknapp, who has a strong relationship with the former England defender after working with him at Portsmouth, to make a move for Campbell - rumours that the experienced manager firmly denies.
The Spurs boss still rates the centre-back however, and has urged Premier League clubs to snap him up in the New Year.
"I couldn't bring Sol to Tottenham, it's impossible. All I said was that I think he can still play Premier League football somewhere," said Redknapp.
"It would be a bigger problem than it would be worth (bringing Campbell to Spurs), but if a manager rang me up from another Premier League club looking for somebody, I'd say 'take him'."
Redknapp was also keen to stress that he would not be offering Campbell the opportunity to maintain his fitness levels by training with Spurs.
"No. I am sure he will keep himself fit and if a club has got any sense they will get him in now, let him train and do a deal for January," he said.
"When January comes round I would recommend him to anyone."
