The 52-year-old head coach made his initial comments after the left-back had not performed well in a recent match against Austria.
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However, after the 6-1 win over the Republic of Ireland, Low has retracted those comments and says he has personally apologised to the Dortmund player.
He continued: "I've looked at everything I said again and have to admit I have come across very harsh. I have apologised to him [Schmelzer] for this."
The Germany boss also stressed the importance of having a strong bench coming into their game against Sweden on Tuesday and Low made it clear he would not underestimate his next opponents.
He added: "There's always a time where you have an Iniesta on the bench, a Torres or a Villa. You need a strong bench.
"It also has to be noted that Sweden are a team with a lot of organisation and are very, very strong."