The appeal was published by the Berliner Zeitung newspaper.
The 18 authors of the letter demand to stop the supply of weapons to the Ukrainian military and call on the government in Kyiv to stop military resistance.
“By supplying weapons, Germany and other NATO countries have de facto made themselves a party to the conflict.
Thus, Ukraine has also become a battlefield for the conflict between NATO and Russia over the security order in Europe, which has been escalating for years.
The authors also stated that, despite "reports of success by the Ukrainian army," it is "far inferior to the Russian one and has little chance of victory."
The letter also argues that arms deliveries and military support from NATO "delay a diplomatic solution."
Earlier, German Foreign Minister Annalena Burbock said that Germany had supplied Ukraine with a large number of weapons, which were not mentioned publicly.
According to her, Ukraine needs heavy weapons and time for excuses not have partners.