The club is 19th in the Premier League after yesterday’s capitulation at the King Power Stadium.
“I don’t think you really want to know what I have said to players – it’s not worth repeating,” said Bruce.
Things went from bad to worse once Ricardo Pereira opened the scoring in the 16th minute. Newcastle had Isaac Hayden sent off late in the first half, and Leicester ran riot after the break.
“Too many felt sorry for themselves,” said Bruce. “We made mistakes, we were badly punished, but to react in that way is the disappointing thing for the players, myself and the travelling support, which was unbelievable.
“It makes the club what it is, unique with that support. We can’t take that for granted. We need to give them something to shout about. To see a team play with heart, passion, before we talk about ability – it has top be a given.
“I can’t defend that unfortunately. It’s as bad an afternoon as I can remember. The whole team, the whole lot of them, were nowhere near what is required to make a fist of it in the Premier League.
“Norwich was nowhere near like that one. That, today, is no comparison to Norwich. We didn’t do anything well enough. That’s the disappointment overall.”
Bruce added: “There are people I haven’t seen play yet – and are waiting patiently. I will look at them in next week or so.”