Veteran German coach Rangnick appears set to become interim boss at Old Trafford for the rest of the season.
United lost five of its past seven Premier League games under Ole Gunnar Solskjaer, who was sacked last Sunday, and Klopp is convinced Rangnick can fix the problems.
"Unfortunately a good coach is coming to England, so that's how it is, to Manchester United," Klopp said.
"He's obviously a really experienced manager who built two clubs from nowhere to proper threats and proper forces in Germany with Hoffenheim and Leipzig.
"He did a lot of different jobs in football but his first concern was always being a coach, a manager, and that's what his best skill is.
"United will be organised, on the pitch we will have to realise that, and that's not good news for other teams.
"Like all coaches, we need time to train with our teams and Ralf will quickly realise he has no time to train because they play all the time.
"But he's a really good man, and an outstanding coach, if it happens, will come to England."
Rangnick has been working behind the scenes of Lokomotiv Moscow this season and his last job as a coach came at RB Leipzig, while he has also worked in senior leadership roles within Red Bull's group of clubs.
Klopp pointed out that his links to Rangnick go back many years, to when he was coaching Mainz and Rangnick was at Hannover in the 2001-2002 season. Both were working in the second division of the Bundesliga at that point, and have crossed paths since at top-flight Bundesliga level.
The fellow German bosses now look set to clash in the Premier League, with United due to visit Anfield in March, having taken a 5-0 thumping at Liverpool's hands last month.
"They always played our opponent a week later, so he called me, the young manager of Mainz, and asked plenty of questions. I was happy that big Ralf Rangnick was calling me," Klopp said.
"They got promoted, we didn't, so he owes me still something. In the football world in Germany, he's very, very well regarded and rightly so."