The clash highlighted security worries in the province where many foreign aid workers and soldiers have been doing aid work since the 26 December tsunami disaster.
"It happened on Saturday, we were attacked ... What we know is one of our soldiers was killed and another was hurt," said military spokesman Major Ediana Sulistiadi on Sunday.
The military had no further details of the clash in Aceh Besar district, just outside the provincial capital, Banda Aceh, and officials from the separatist Free Aceh Movement (GAM) rebel group were not available for comment.
GAM and the Indonesia's military often exchange blame for violence in the gas-rich province on the northern tip of Sumatra island.
It was the first reported clash between the military and rebels since peace talks in Finland last week, at which Stockholm-based GAM officials said they were ready to drop their independence bid in return for some form of self-government.