The Syrian Revolution General Commission said the deaths occurred in December in Ghouta’s Arbin village, which is around five miles (eight kilometers) away from Damascus.
The alleged blockade imposed by Assad forces was preventing the flow of medical supplies and humanitarian aid in the area. The situation was becoming worse day by day, especially with new diseases starting to emerge in the village, the commission said.
Around 216 people, including 150 children have died of starvation in the under siege Ghouta area within the last two years, it added.
The commission called for urgent humanitarian aid for the affected people in the area.
An armed struggle launched by the Syrian opposition forces against President Bashar Al-Assad began in 2011.
More than 190,000 people have been killed in Syria since the conflict began, according to UN figures published last August.
Amnesty International estimates that more than 10 million people have been forced out of their homes; and at least four million of them have become refugees, mostly in Turkey, Lebanon, Jordan, Iraq and Egypt.
The Syrian Revolution General Commission represents a unified coalition of Syrian opposition groups that aims to establish a democratic set up in Syria.