A disappointing 2-2 draw against Cologne on Saturday left Dortmund in danger of missing out on the top four, which would increase the likelihood of Haaland leaving at the end of the season.
The 20-year-old's agent Mino Raiola recently said that there were 10 clubs who could afford to sign the player but Sammer has urged Haaland to stay put.
"I would recommend for Erling to also see the value of Borussia Dortmund," Sammer told Sport Bild. "The club has given him a lot. From here, he can only go to a handful of clubs."
Haaland has been one of the biggest stars of this season with 33 goals in 31 matches for Dortmund this term and, along with Paris Saint-Germain forward Kylian Mbappe, has been tipped to regularly fight for the Ballon d'Or once Cristiano Ronaldo and Lionel Messi stop playing.
Dortmund do not want to sell in the summer and a release clause reported to be between €75 million and €100m in his contract can only be triggered from 2022.
Sammer said he believes Haaland should make sure he only leaves Dortmund when the time is right, citing Robert Lewandowski's success and Bayern Munich and Ousmane Dembele's struggles to adapt at Barcelona as examples.
"When Erling makes the next step, he must be the finished product, perfect," Sammer added. "He is very, very good.
"He must improve some details. Robert was complete when he left for Bayern [on a free transfer in 2014]. It was clear: He went straight into the starting lineup.
"But as a counter-example Ousmane Dembele maybe left for Barcelona a moment too early. Erling is far in his development, but he is not complete."
Barca, Manchester City, Manchester United, Real Madrid and Bayern have been linked with Haaland in recent weeks, but Sammer, who acted as a sporting executive at Bayern from 2012 through to 2016, said he could not imagine the Bundesliga rivals will make a move for the Dortmund attacker.
"This won't happen today or tomorrow because Bayern already have Robert Lewandowski," Sammer said.
Asked to explain the differences between Lewandowski and Haaland, Sammer said: "Erling has other factors. He is more forceful, Lewandowski is smoother. Robert is fast on the distance but does not have as much pace as Erling. Robert has more experience in the tight spaces, because of his career path he has the perfect judgement for situations.
"Robert is absolute world class, Erling is on his way there. He has the hunger in him. I have never seen anything comparable in terms of stats and lust for goals at this age."