"I didn't like my team today and we deserved to lose, it is as simple as that," Mourinho told BT Sport.
"I thought they were in the game more than us, they were committed more, they fought more and I don't think we didn't do enough to win. If somebody had to win it then it was Newcastle who deserved it.
"We were not sharp enough, we were not intense enough. We were not fast with the ball, we were not aggressive enough and there was a chance waiting to happen [for Newcastle] and that's exactly what happened."
The defeat leaves Chelsea third in the Premier League.