The Croatian officer received the medal for his role in an operation to rescue a missing German soldier after a Taliban attack on a provincial reconstruction team in northern Afghanistan.
During the ceremony in the German embassy, Ambassador Fischer said that Captain Poljak had been among the first soldiers to apply for the rescue operation.
"His professional and exemplary conduct has substantially contributed to the safety and security of the camp and to the strengthening of cooperation between the Croatian and German armies," the German diplomat said.
Captain Poljak, who had spent one year in Afghanistan, said at the ceremony that this medal was also an award to his unit, the Croatian Armed Forces and the Defence Ministry.
Germany has 5,000 troops in Afghanistan while Croatia's contingent consists of 330 troops.
In attendance at the ceremony were Croatian Defence Minister Davor Bozinovic and high-ranking Croatian Army officers.