Markus Potzel, Germany's Special Envoy for Afghanistan and Pakistan in a tweet on Friday made the announcement and said a vast majority in German Parliament voted for an extension of Germany military's contribution to the Resolute Support Mission in Afghanistan.
Thirteen American service members were killed previous year in Afghanistan.
Their names were being withheld in order to first notify family members.
The statement did not specify the location of the combat or say who the soldiers were fighting.
A spokesperson for the coalition told CNN that "the incident is under investigation and we have no additional information to provide".
Fighting continues across Afghanistan more than a week after the latest round of negotiations between the United States and the Taliban ended in Qatar, as Washington seeks an end to the almost 18-year war.
As you can imagine, more people are reading The Jerusalem Post than ever before.
Violence has persisted in Afghanistan even as Taliban militants have held negotiations with USA officials about a peace settlement.
It brings the total number of USA service members killed this year in the country to four, according to a tally by The Associated Press.
The Afghan government has complained it is being left out of the talks, because of the Taliban's refusal to negotiate with what they consider "a USA puppet".
Both sides have agreed on the planned withdrawal of US forces, however there has been division over what a timeline for the withdrawal will look like.
Despite the talks, Afghanistan is suffering from crippling violence, with a record number of civilian casualties previous year.
Parallel talks have also been held in Moscow, and in an effort to expand internationally, the US chief negotiator, Afghan-born Zalmay Khalilzad, is hosting his Russian, Chinese and European Union counterparts in Washington on Thursday and Friday.