Borussia Dortmund’s squad was preparing to leave their team hotel for the Westfalenstadion and a Champions League clash with Monaco.
But three explosions targeted at the team coach, which resulted in defender Marc Barta going to hospital for treatment on his hand, meant the game did not go ahead.
Monaco beat Dortmund 3-2 in the rescheduled fixture yesterday.
The Bundesliga club have criticised UEFA for their rescheduling of the match so soon after the incident.
And Liverpool manager Klopp, who oversaw a period of success at Dortmund between 2008 and 2015, says he was shaken by events that unfolded in Germany.
“I don’t think what I say is too important,” he said ahead of Liverpool’s clash with West Brom on Sunday (1.30pm).
“Everybody can imagine it was a difficult moment for me because I don’t know how often I was in the team hotel with Dortmund.
“I know exactly the road. A lot of my friends were in the bus. I was on the way home from Melwood and Matt called me and told me something happened.
“I was really concerned, scared for them. In the first moment it was a bit of relief, then you hear the more information you get the more serious it got.
“I had contact with people but I didn’t want to bother them with my silly questions. I was waiting with the rest of the world. The last thing I thought about was the game.”
Asked about the game rescheduling, Klopp said: “I can 100 percent understand both sides – it was difficult to find another date. I think everybody could understand if you couldn’t play it.
“I was really proud of Borussia Dortmund. When they played the game they tried to give the best.
“I saw the faces of my former players and I saw the shock in their eyes and that was really, really hard.”
Dortmund are set to play Eintracht Frankfurt in the Bundesliga on Saturday before the reverse fixture with Monaco next Wednesday.
And Klopp concedes the squad may not be best prepared for their games following the attack.
“It will take time to deal with it. I’m pretty sure the people who make the decision afterwards, if they had been in the bus they would not have played the game,” he said.
“If you are not in the bus you cannot imagine how it is exactly.
“I am like all the other football fans in the world, the only difference is I know all of them.”
Asked about whether or not it is difficult to carry on as normal, Klopp said: “No. It’s not. It’s difficult to speak about, but in the world a lot of difficult to understand things happen.
“As human beings we all think about this but as long as we are not directly involved, it’s hard but life goes on.
“I see it like all in the world see it. We have to carry on. We will and we can. We can concentrate on football and training.”
