Jürgen Klopp has said he was honoured Sir Alex Ferguson considered him as a potential successor at Manchester United but that the timing of the approach, coupled with loyalty to Borussia Dortmund, prevented a move to Old Trafford in 2013.

The Liverpool manager faces United for the first time in a competitive fixture on Sunday having been approached to replace Ferguson when the Scot retired three years ago. Ferguson claimed in his latest book that Klopp, Pep Guardiola, José Mourinho and Louis van Gaal were considered for the Old Trafford job but their unavailability in 2013 paved the way for David Moyes’s brief tenure.

Klopp admits he was flattered by Ferguson’s interest, and by his concern that Brendan Rodgers’ successor at Anfield has the talent to revive Liverpool’s fortunes. The 48-year-old returned the compliment on Friday by describing Ferguson as “the John Lennon of football” and arguably the greatest manager of all time. However, Klopp insisted his commitment to Dortmund – who reached the Champions League final at Wembley in the season Ferguson stepped down – meant he never entertained the idea of swapping Westfalenstadion for Old Trafford.

“We spoke,” the Liverpool manager said. “We spoke not a lot but, for me, it was a lot. It was a big honour, the whole talk, to be honest. There was a time [when United were interested] but I could not leave Dortmund. That is it. You are in April and you are in the middle of the planning for next season. You have this player and this player and this player who is coming in but then you are not there any more? That doesn’t work. Not in my life anyway.

“I did not hear about a real offer but, if there was, I could not have done it. I first had to finish the job with Dortmund and then think about other things. Maybe that is not the smart way but that is my way. Of course I was loyal to Dortmund. It was the same at Mainz.”

The position of United’s current manager, Van Gaal, has been in doubt this season amid criticism of the team’s style of play and their slide from the Premier League summit to sixth going into Sunday’s game at Anfield. But the Liverpool manager claims sacking the Dutch coach, a former rival at Bayern Munich during his time in the Bundesliga, is not the answer to United’s search for success in the post-Ferguson era.

Klopp said: “The pressure [Van Gaal is under] has an affect on your whole life but, in my case, not on how I handle my team or anything like this. It is always the case if things don’t run the way you want – you have to think about whether to change things or not to change. Both decisions are really important. Life is not that nice. I know the whole world is watching football managers and thinking: ‘They are really well paid’, so no one cares about a manager’s feelings.

“I didn’t watch too much of these things at United but I heard about it. I know Louis is not too happy with the media at the moment but I think in life it is important sometimes to switch and think about how it would be on the other side. OK, fine, you would have all this money but also all this pressure so it is not nice. If you want to change things in football it is not OK that you think: ‘Bad, bad, bad – go.’

“That is not a change. If that was the solution I think Man United would have done it. But it is not a solution so they have to carry on. It is not our problem, but it is a manager’s problem. It’s not the case that the sun is shining every day as afootball manager.

“It’s like with you [the media] with me when I came here. First it’s ‘Yeh!’ [gives a thumbs-up] then it’s ‘Erm’ [thumbs to the side] then it might be ‘Ooh’ [thumbs down], so then I am alone on the side and we might have the same situation here.

“I will not have changed as a human being but you are not interested in this. That’s no problem. I am only interested in what my friends and family think about me.”

Klopp is relishing his first experience of Liverpool versus United, describing it as a derby. “I love derbies,” he said. “They are the salt in the soup.”

Liverpool will have the same squad available as for Wednesday’s 3-3 draw against Arsenal – with neither Dejan Lovren nor Daniel Sturridge back from hamstring injuries – and their manager insists the magnitude of the occasion has not been diminished by the north-west rivals’ league positions.

“It is not the biggest game in terms of the table – if you went on the table it would be Arsenal against Leicester,” Klopp said. “But we cannot and should not ignore history in life. Historically it is a really big clash and we have to accept that we are protagonists. Should I say to the players: “Oh, come on, it’s only sixth v ninth so stay cool”? No, it is a big game. It is a big game for us and we want to win.

“I can’t change where we are in the table. I think we are all on the way and we are trying to improve. We are trying to make big steps but we have to respect that sometimes it doesn’t work like that. But that doesn’t change our target – we want to improve, we want to get better and we want to be higher in the table. And we want three points against a strong squad like Manchester United. It is not going to be easy but it is possible.

“That’s all we need. Hopefully we can celebrate after the game. That is all I want in football. I love football because of the intensity of the game and, with this game, the intensity starts before so that’s good.”