Ballack, the Bayer Leverkusen midfielder, has been told he needs to regain his best form after spending three months on the sidelines with an ankle injury that kept him out of the World Cup.
"We had a good and truthful discussion," Low said after talking to Ballack on the phone.
"Michael is on a good road back after three months out with his injury and everyone is satisfied with his recovery. It is important now for him to find his top form with Leverkusen."
Low called up 17 players who were part of Germany's third-place finish at the World Cup for his 21-man squad to face Belgium in Brussels on September 3 and Azerbaijan in Cologne four days later.
Ballack was injured in last season's FA Cup final while playing for his former club Chelsea. After sitting out the World Cup in South Africa, he returned to the Bundesliga and Leverkusen.
The 33-year-old, who has won 98 caps, played the full 90 minutes in Leverkusen's 2-0 win over Borussia Dortmund in the Bundesliga opener last week.
With Ballack out of the squad, Loew has more time to decide on Germany's new captain. Philipp Lahm assumed the role at the World Cup and has said he wants to stay on as captain.
Ballack has said he wants the armband back once he is recalled to the team.
Low recalled defender Heiko Westermann and midfielder Christian Traesch as well as keeper Rene Adler, all of whom were injured weeks before the World Cup.
Bayern Munich keeper Hans-Jorg Butt, who was a surprise inclusion in the World Cup squad, was dropped.
"It was understood that Rene would come back," Low said. "After his operation he has shown until now that he is in good form."
The injured Arne Friedrich, Jerome Boateng, Piotr Trochowski and Dennis Aogo, all members of the World Cup squad, were omitted.
Squad:
Goalkeepers: Manuel Neuer (Schalke 04), Tim Wiese (Werder Bremen), Rene Adler (Bayer Leverkusen)
Defenders: Holger Badstuber (Bayern Munich), Marcell Jansen (Hamburg SV), Philipp Lahm (Bayern Munich), Per Mertesacker Werder Bremen), Sascha Riether (VfL Wolfsburg), Heiko Westermann (Hamburg SV)
Midfielders: Cacau (VfB Stuttgart), Sami Khedira (Real Madrid), Toni Kroos (Bayern Munich), Marko Marin (Werder Bremen), Thomas Muller (Bayern Munich), Mesut Ozil (Real Madrid), Lukas Podolski (Cologne), Bastian Schweinsteiger (Bayern Munich), Christian Traesch (VfB Stuttgart)
Strikers: Mario Gomez (Bayern Munich), Stefan Kiessling (Bayer Leverkusen), Miroslav Klose (Bayern Munich)
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