The Senegal striker, who scored his 10th goal of the season in Monday's 3-0 win over Wigan, has a condition in his contract which had to be activated by July by any club wanting to take advantage of it.
This failed to happen in the summer, meaning that while the current deal remains in place, the clause will continue to be activated during each window.
With Ba's current deal expiring in 2014 and the next transfer window looming, the Magpies are determined to secure the services of the 27-year-old on a long-term basis.
Pardew told Sky Sports after the win over Wigan: "Demba is a player who loves it here and he understands it is a football city.
"We've tried to do a deal with him and take the clause out and that's probably where the speculation is.
"The clause is always hanging over us and it makes it difficult for us, the club and him. We accept that and that's the way football is.
Asked about Ba reaching 10 goals for the campaign, Pardew added: "He has been brilliant for us.
"At times, he is important in the dressing room and everything else that he brings to the club.
"I have tried to encourage him to be more vocal in the dressing room because he's a leader, but the 10 goals is a nice target for him."
He added: "But I was so pleased for [Vurnon] Anita. To come from the Dutch champions to come to us having not been part of what was a great season last year, he must have thought, 'What have I done?'
"I am very pleased he won tonight, and I honestly thought he was the best player."