The Reds were beaten 1-0 at Anfield via Callum Hudson-Odoi's strike.
“It was a very disappointing day because of the result and also most of the performance,” said Van Dijk. "We were too rushed and we lost too many second balls.
“You can sometimes lose a challenge but you have to be ready for the second one and every time there was a second one they were on the right side of it. They did their job very well and we weren’t good enough.”
He also insisted international week was no excuse.
“Everyone is coming back from different places and playing a different way, but still I think even though we weren’t at our best we created chances and should have done better,” Van Dijk said.
"It's a performance we are definitely not happy with and we expect a lot better from ourselves. Losing at home is definitely something that can’t happen, but we have to turn it around pretty quickly.”