Balan was a member of Syria's relief agency and the head of planning at the Social Affairs Ministry, The New York Times reported Friday.
A resident of the area said the attack on Balan was carried out by four assailants in the Mezzeh district, which is generally considered well-guarded.
The witness said one of the gunmen entered the Chinese restaurant where Balan was eating and shot him with a silenced pistol while the other three assailants waited outside.
A slightly different version was offered by the Syrian Observatory for Human Rights, which monitors a network of anti-government informants. The Observatory said all four attackers entered the restaurant and one of them shot Balan.
The official Syrian news agency SANA blamed "terrorists" for the shooting.
Meanwhile, the Syrian Network for Human Rights said it had documented 125 people died in Syria Friday. The group said the victims included 19 people killed by government troops in a massacre at a checkpoint in the Derbaalbh-Homs area as the civilians were trying to leave the area.
The group also said 31 children, a dozen women and 18 armed rebels died. Fifty-eight were killed in Damascus and surrounding area.
The casualties had not been independently verified.