At least 13 people were killed and 17 wounded in the raid on Maadi in northeastern Aleppo on Sunday, according to the Syrian Observatory for Human Rights.
In another part of the city, three children died and a dozen people were wounded when rebel rockets struck a regime-held district, the Observatory said.
The monitoring group said the Maadi deaths happened when the regime aircraft "dumped a barrel bomb of explosives on a building".
The death toll could rise because of the number of seriously injured people, it said.
The Observatory reported the death of only one child, but the local resident said at least four were killed.
An AFP journalist on the scene saw a building with its roof caved in and other major damage, while debris was strewn all around.
Civil defence volunteers from the rebel districts hastened to clear the rubble by hand and unearthed a man's body, covered in white dust with a bloody head.
Other volunteers pulled back rubble with a pickaxe while a childlike body in a plastic cover was taken away on a stretcher.
Local people gathered up what was left of boxes of fruit and vegetables, spread out over the road.
The residents said the raid happened early in the morning.
"People were asleep… a grandfather emerged safe and sound but his three sons, all married, and their children, we still don't know what has happened to them," one resident said with emotion.
"They found four children torn apart after the helicopter dumped its barrel bomb, may God curse him," the man said, referring to President Bashar Assad, the focus of a three-year struggle by rebels to overthrow him.
Residents said the raid appeared to target a district where a popular souq is located.
Last month Human Rights Watch said the number of rebel sectors hit by barrel bombs had almost doubled in five months.
The regime has pressed on with its barrel bomb campaign despite a United Nations resolution on February 22 banning their indiscriminate use in populated areas.
HRW described barrel bombs as "cheaply made, locally produced, and typically constructed from large oil drums, gas cylinders, and water tanks, filled with high explosives and scrap metal to enhance fragmentation, and then dropped from helicopters".
Translated and edited by The Syrian Observer