Liverpool go into the first-leg on the back of their 2-2 draw with Manchester United on Sunday, where Alexander-Arnold was criticised for his performance.
But Slot said: "I think we were all disappointed not only Trent Alexander-Arnold, we were all disappointed.
"First of all about the result. Parts of our game we weren't completely happy with. It wasn't only Trent, there were more things we could have done better.
"Trent didn't play his best game, but some others also didn't play their best. If you play 50, 60 games in a season, one of them won't be your best performance. Maybe we should highlight these players are playing so well despite playing two games in a week.
"I talk with my players, if there's anything worrying them they share it with me.
"What I have shared with the players is what we have done against Manchester United, and what we are doing well against Manchester United.
"That is what we are focused on. I am not focused on social media posts or what people are saying. If you do that as Liverpool manager you will have no life, because people are always talking about us."
He also stated: "I've spoken to him and others individually as well which you do after every game. I spoke to him before the game as well and the things we shared I will not say here.
"It wasn't his best game and I showed him where to imporove. But you do this after every game. Sometimes you show them what they did really well. But I do this with everyone.
"There are always things you can improve, but in general they worked really hard. We were unable to get the best result but we still got a result.
"If Mohamed Salah misses a penalty against Real Madrid he's distracted by his 'contract situation'.
"If Trent doesn't play well he's distracted by his 'contract situation'.
"If everybody plays well, nobody is distracted by their 'contract distraction'."