The Brit, who recently confirmed that he would miss next month's ATP World Tour Finals following back surgery, is currently in fourth place in the rankings.
Despite Murray's claims that he is more interested in winning Grand Slam titles, Becker believes that the Wimbledon champion should turn his attention to getting to the top of the men's game.
"He hasn't talked about [becoming world number one] yet, which has surprised me," the German told Sky Sports News. "After winning Wimbledon, that would be the next logical step.
"He hasn't said it yet because I don't think he was prepared for it in his head and I think that is the process he is now. What's the next big goal? It has to be becoming number one."
Six-time Grand Slam champion Becker spent a total of 12 weeks at the top of the ATP rankings before his retirement in 1999.