The Bundesliga side's general manager, Klaus Allofs, said he has already begun to identify targets for the January transfer window - with Kagawa and de Bruyne reportedly high on his shortlist.
And he told Bild in Germany that the club will not hesitate to move if the right player becomes available for the right price.
"We want to do reasonable transfers, just like with Luiz Gustavo," said Allofs.
"That was exceptional in terms of transfer fee and dimension. We want to continue a selective reinforcement of our squad. Not in a heave-ho style."
Wolfsburg beat Arsenal to the signing of Gustavo over the summer. Like United's Kagawa and Chelsea's de Bruyne, the Bayern Munich midfielder was struggling for playing time at his Champions League club.
De Bruyne impressed in the Bundesliga last season with Werder Bremen. He spent the season on loan from Chelsea before returning to Stamford Bridge for this campaign.
But despite a positive start to life under Jose Mourinho, the Belgian international has fallen out of favour at Chelsea and is now linked with a return to Germany.
"At Werder, I have seen just how good de Bruyne is," continued Allofs.
"If such players are possible, you of course think about them. But we should not raise the hopes of our fans. In the end they comment: 'Once again, you failed to sign him'."
Wolfsburg may have an opening in their first team for a player like Kagawa or de Bruyne as current first-choice playmaker Diego is out of contract at the end of the season.
Kagawa has struggled to get a regular start under new United boss David Moyes, and the Japanese international has also been linked with a January Old Trafford exit - former-club Borussia Dortmund are reportedly interested.