Low explained it was a "very close decision" between Sane and Bayer Leverkusen's Julian Brant, who ultimately got the nod, adding that Sane, "has not arrived in worldwide matches yet".
Speaking on Monday, Low underlined the importance of multi-functional players in a squad for a major tournament.
Former Chelsea, Bayern Munich and Germany midfielder Ballack used social media to give his take on the exclusion of the PFA Young Player of the Year.
This season, Sane has been in electric form for Guardiola's side, scoring 14 goals and assisting 19 times in 49 appearances, averaging a goal contribution every 1.48 matches.
'[Julian] Draxler, [Marco] Reus and [Thomas] Muller are set.
"Leroy has a huge talent and he'll be there again, and we'll have to work more with him again from September onwards".
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With the player also putting in a less than impressive performance in a World Cup warm-up game against Austria on Saturday.
"It was a very close decision. If it was a 100m race, it would have been a photo finish".
"Of course I am disappointed", the Bayer Leverkusen goalkeeper wrote.
"It's like being at the airport check-in counter en route to Moscow and you are not allowed to board the plane".
Germany will face Mexico, Sweden and South Korea in Group F in Russian Federation.
Sources close to the German camp claim Sane was axed because some of his behaviour and his attitude did not go down well with his teammates and coaches.