The temporary injunction was handed down by a Hamburg court and requests a response from T-Mobile's parent company, Deutsche Telekom, within two weeks.
Deutsche Telekom has confirmed (translation) the ruling, which can be overturned as part of an appeals processes.
For its part, Vodafone -- which at one time was in the running for its own exclusive contract to sell iPhone to parts of Europe -- claims that it took the matter to court out of fears that other handset makers may follow Apple's example and begin tying their handsets to specific providers, further shredding the German wireless market.
Vodafone Germany chief executive Friedrich Joussen in a statement said his firm's goal is not to prevent sales of the device but rather allow for consumers to purchase iPhones without binding themselves to long-term agreements with any one carrier.
"We want it to be available to buyers without a mandatory calling plan," he said. "If I had wanted to halt sales, I could have, but I didn't."
A definitive ruling on the matter is expected within two weeks.
Update: Coverage of the matter by Dow Jones differs somewhat from the local German press by implying that the temporary injunction restricts any and all iPhone sales in Germany, rather than just those that would be sold with a contract. But due to the agreement between T-Mobile and Apple that iPhone only be sold with a service plan, it's likely that both scenarios would produce the same result temporarily -- a halt to iPhone sales in Germany.