Arne Slot's Liverpool side picked up their third consecutive win of the season after taking apart United which has left many fans feeling deflated.
"I think the first half an hour was okay," said Ten Hag. "We made a mistake in defensive organisation for the disallowed goal but we were in the game. It was equal, level, and then we had a great structure in building up but then made a big error and, with the quality of Liverpool, they took benefit of that. They took their chances so well. We have to be humble. We have to give the compliments to Liverpool but, of course, we are not happy.
"I'm very disappointed, especially when you lose 3-0 to Liverpool. The game is over and we have to live with the result. We have to continue, bounce back and we need to improve the team. Individuals have to improve and, also fitness-wise, we have to improve. We will be fine. We are going for trophies and we have a lot to play for."
The Dutchman also spoke on Marcus Rashford who had a poor game as many called for him to be taken off.
"First of all, I'm happy as it's a good question but, first of all, Marcus (Rashford) created two great chances for Zirkzee. In the second place, it was Garnacho's first start and Zirkzee's first start. We know Rashy can play centre-forward and one of the ideas was to bring off Zirkzee and Garnacho and leaving Rashford on. He created two very good chances. I know if he keeps working, keeps fighting like he is now, it will come and he will score goals."