It comes after the Blues were this week credited with a move for the left-sided defender as Danny Cowley turns his attention to recruiting a wing-back.
But with the 25-year-old Black Cats Academy graduate penning a new contract at the Stadium of Light in the summer, a deal – according to Johnson – looks potentially hard to strike.
Johnson told The Northern Echo: ‘A contract for me is an important thing and you should stand up to it or somebody comes in and meets the terms of those contracts.
'I don't think I realised how much it would mean': ex-Cardiff City and Bristol City man's Portsmouth admission as he chases winning Fratton feeling after homecoming
Former Portsmouth, Sunderland and Millwall ace Aiden O'Brien suffers setback as frustrating start to life at Shrewsbury continues
Danny Cowley makes Portsmouth team selection admission following Cheltenham win - and gives honest assessment of current squad amid early-season promotion hopes
The role ex-Leicester City, Birmingham City and Charlton Athletic man wants to maintain at Portsmouth after guiding city's young gems at Reading
How golden boot odds have shifted for Portsmouth, Ipswich Town, Plymouth Argyle, Bristol Rovers and Peterborough United front men after start to season
‘I think that’s what Kristjaan Speakman (sporting director) means more than anything.
‘Anything done, going out, is on our terms because we’ve got these players under contract and we’re no under financial restraints.
‘If we were to accept an offer, it would be because we believe we could use that money well either within the club or on other areas of the pitch.’
Despite negotiating fresh terms with the Wearsiders in pre-season, Hume has struggled for game time this season.
In total, he’s made eight appearances in all competitions under Johnson – a lack of action which has prompted speculation regarding the player’s future.
However, the Sunderland head coach reaffirmed his admiration for Hume ahead of tomorrow’s meeting with Pompey. .
He continued: ‘Denver is in a situation where he’s under contract with us.
‘I think Denver would be disappointed in recent weeks. I know he’s keen to play in every minute of every game but that’s what you want.
‘Obviously, we had the whole saga over the summer with the contract, that was put to bed and I’ve been happy with Denver.
‘There has been issues in between that. Whether it be fitness, form, Covid, all those bits and bobs but at the same time Denver is in a really good place and ready to jump in at the drop of a hat.”
‘I think you’d consider anyone that wasn’t happy for whatever reason but it can’t be at the detriment of the first-team and Sunderland’s challenge to go and get promoted.
‘When you sign a contract, you sign a contract. Whether it’s my contract, your contract. I think sometimes in football, people forget about those contracts and this is definitely nothing to do with Denver.’
A message from the Editor, Mark Waldron
Get 30 per cent off our sport subscription, which gives readers unlimited access to all our Pompey and grassroots coverage for just 9p a day, by using the promo code JanSports30. The deal expires at midnight on January 31.