The 24-year-old joined the north London club for a club record fee of €50 million after making 159 appearances for the Spanish giants, and Low simply cannot understand why los Blancos chose to get rid of him.
"For me, it is a bit incomprehensible that Real Madrid would get rid of one of their best players, who is of a high quality and looked more decisive than ever last season," Low told reporters.
"Mesut still needs to feel as though he has complete confidence from his coach.
"From what I heard from Madrid ahead of the transfer, you could feel that the trust was no longer there 100 per cent. Arsenal tried hard to sign him. That did him good.
"Ozil's Arsenal move will be a good transfer for the national team because he will play for a team which has an overall great technique - that is good for him."
Germany will be without Bayern Munich's Mario Gotze for their crucial World Cup qualifiers starting this week, and Low admits he is anxious over the midfielder's fitness following injury problems earlier this year.
"For him it's really bad, for Bayern as well, suffering another major injury, shortly after recovering from a previous one. He will have to fight back," Low said.
"I hope he finds his rhythm back quickly and he will be an outstanding player.
"In 2012 he suffered the same with being out for six months. Now the World Cup is coming closer, so we really hope he won’t be injured too much and too often."