Dave Jones was unhappy that the officials had missed a genuine penalty claim.
He said: "It was a stonewall penalty when the Newcastle player handled the ball, but if you make a defensive mistake like we did in the first half, you have to suffer the consequences.
"We had good positions to get in on goal and dominated the game for long periods, but at this level, in a tight match, you do expect the officials to get it right.
"We knew it was going to be a tough game both on and off the pitch, but we had to break 10 men down and we have to be wiser.
"I have no complaints about losing the match, but when you lose you always feel hard done by, especially when the referee has to be brave under those conditions.
"Newcastle stopped our flow and Alan Smith was probably unlucky to be sent off, but they have Premier League players and know exactly how to put their bodies on the line when necessary."
Newcastle caretaker manager Chris Hughton said: "These are very tough games for us, but we limited Cardiff to only a few chances throughout the game.
"I haven't seen the penalty incident, but it was a game of high tempo, and that was only one of several incidents in the match.
"I think Alan Smith was very unlucky to be sent off, and possibly his reputation went before him.
"He is in the thick of most things in the centre of midfield, and that is probably why he is singled out more than others.
"The games are coming thick and fast, but we now have to maintain the impetus as we have started well. It will be a few weeks before we know exactly how we are doing."