The statement provided no further details about the attack and did not identify the dead service members.
The news came after roadside bombs and insurgent attacks killed at least 23 people this weekend in southern Afghanistan. The victims include two NATO service member, five police officers, and 16 civilians.
The civilians who were killed in a trio of blasts in Arghistan district included women and children. Several others were injured in the area where militants are trying to reclaim territory.
Two NATO service members were killed - one in a roadside bomb explosion on Saturday and the other during an insurgent attack on Sunday. So far this year, at least 231 NATO service members have been killed in Afghanistan.
The attacks come as Secretary of State Hillary Clinton was in Afghanistan to announce a new relationship with the U.S. Afghanistan is America's newest major non-NATO ally, which means it will have access to American military training and supplies.
The new designation is designed to smooth cooperation between the two countries as U.S. troops withdraw.
The Associated Press contributed to this report.