The champions were on course to reach 98 points going into Sunday's final SPFL Premiership game of the season against Dundee United and led St Johnstone 3-1 with only six minutes left of their game in Perth on Wednesday night.
Even beating United will take them to 99 points for the campaign, meaning they cannot emulate the club's 2001/02 side under Martin O'Neill, the only team to reach 100 points in a Scottish top-flight campaign. The current side are already far ahead of last season's league-winning points total of 79.
Van Dijk said the players were angry with themselves after Wednesday's 3-3 draw. Celtic can reach a century of league goals for the season if they score one more against United, but 100 league points is now beyond them. "It was something that we wanted to do and it's always nice to have 100 points and 100 goals as well," said van Dijk.
"We still have targets and we wanted to reach the 100 points. That we can't now is a big disappointment for all of us. But we've still got the chance of 100 goals and that's what we want to do.
"It's not hard for us to motivate ourselves. But it was just a very bad game [against St Johnstone] and very disappointing. We were definitely angry afterwards.
"We know that we can play much better and it was such a bad, bad first half. The second half was a little bit better. We shouldn't have given it away when we were 3-1 up.
"We were poor, definitely. It was very bad. I don't know the reason behind it. But we know we can do better and we need to. We have one more game left and we need to show the fans that we can get revenge for the St Johnstone game."
Celtic will be presented with the SPFL Premiership trophy after Sunday's game. "We definitely want to win and make it a beautiful day. We need to bounce back and show everyone and the fans why we are the champions of Scotland."