Goals from David Edwards and Sylvan Ebanks-Blake earned Dean Saunders a first win as Wolves manager and condemned Millwall to a seventh defeat in eight games.
"I thought we lacked passion and heart, the basic things you need - especially for this club," said Millwall boss Jackett after a fourth straight defeat at The Den.
"It's an apology to the people that paid to see that. You accept you will lose games, but that was a poor performance.
"We've had two good showings before this game, and I would have expected it to continue. I didn't think we were out of the game at any stage, looking at Wolves' position, it was always open, but we didn't show enough organisation or desire to make it happen.
"I don't think there's a fear of playing here, but if there is I don't accept it. If you have a bad first 20 minutes, you have to bounce back. It's only 1-0. Even in the last 15 minutes, it's only 2-0.
"Why can't we win a game 3-2 from a poor position? Too many times we've fallen away.
"I'll try and make the right changes - and there will be changes - for Sunday (against Blackburn)."