Palace had taken seven points from their previous three home games, keeping clean sheets in all of them, but were blown away by the Magpies at Selhurst Park on Saturday.
Yohan Cabaye opened the scoring after 25 minutes, and Danny Gabbidon scored an own goal six minutes before the break.
"We made it tough," admitted Pulis. "We've had plaudits over the last couple of weeks because of the way we've played and how we've gone about our business, but today we were poor.
"The first two goals are awful goals from our point of view. We've got the two central midfield players chasing a goal-kick, and then the right-sided midfield player is out of place as well. From one header, they're on our back four.
"For the second one, obviously, we had a problem down our left-hand side stopping crosses. The cross goes in there and unfortunately Gabbs (Danny Gabbidon) gets a touch and it goes in the back of the net.
"So from two situations that we've been very good on over the past couple of weeks, we've been poor today. And you have to give Newcastle credit - from that point onwards, they controlled the game.
"I can't criticise the players. They've been brilliant since we've come in. But you have to show resolve in every game. You can't be doing stuff off your own back. It's a lesson we have to learn very quickly."
Pulis admitted it was a blow to lose the services of midfielders Kagisho Dikgacoi and Stuart O'Keefe to muscle complaints before kick-off, a situation which meant Joel Ward had to play in the middle of the park.
"To lose two midfield players was very difficult for us," added Pulis. "If we'd have been able to pick the team, Wardy would have played at left-back because the back four has looked really solid.
"But that's what happens in football. We have to take it on the chin and move on. We have two very tough away games now, but this was always going to be a tough period for us."
Palace go to Aston Villa on Boxing Day before an even more daunting trip to Manchester City.
Pulis did see signs of improvement after making a double substitution at half-time, and pointed to Cameron Jerome's miss midway through the second period.
"We did better second half, in terms of nullifying what they had. We didn't look so stretched," he continued.
"With 20 minutes to go, if Cameron takes that opportunity and scores - as dominant as Newcastle were in lots of ways - it's a different game."