The pilot of the IAR 330-Puma helicopter had reported unfavourable weather conditions and had been called back to base before the crash, the ministry said. The helicopter fell near the village of Gura Dobrogei in eastern Romania, Reuters reported.
The ministry initially said the crash had killed five soldiers, but later updated the death toll.
"I give my profound regret and full compassion for the loss of seven soldiers from the Mihail Kogalniceanu air base," Romanian President Klaus Iohannis said.
The fate and location of the MiG plane and its pilot were still unknown. Romania, a European Union and NATO member, plans to phase out its MiG planes and is flying F-16s.
MP/PR