United drew 0-0 with Manchester City last weekend, before a goalless 120 minutes preceded their League Cup penalty-shootout elimination at the hands of Middlesbrough in midweek.
After failing to find the net against Palace, the Dutchman bemoaned his side's inability to control the match and was left frustrated as they mustered just a single shot on target.
"When you are not creating so many chances you cannot complain," he said.
"Against Middlesbrough I thought we had chances to finish, so that is of more concern. But today we had no chances to win it.
"Today I think it was obvious that Crystal Palace started very well in this game, they won every second, third ball and we didn't touch it.
"Then after 15 minutes we came into the match, had positional shape and made chances, like Ander Herrera in the last minute of the first half.
"In the second half Crystal Palace had more strength. When you play like Crystal Palace did with the long ball the pressure is always on our goal.
"Still, I think we could have scored in the second half but we were not the better team today and that's a concern.
"I cannot train anymore because we have to recover, recover, recover. We have a game every three days so I have to speak more.
"The most important thing is to score in the next game."