Haller went unpunished for a nasty tackle on Zimmerman, who left the London Stadium wearing a protective boot on his ankle.
"I do not understand this, to be fair," Zimmermann said. "I mean I'm certainly not a player who wants to see others get a card or be sent off.
"But after the physios came on I thought I could stay on the pitch and I thought he would at least get a booking - but when the ref told me, if anything, I was surprised."
Zimmerman will undergo scans this week to learn the severity of his injury.
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