The Britain-based Syrian Observatory for Human Rights said 70 people, including 30 children, were also wounded in yesterday's attack, adding that the shelling was a violation of a ceasefire agreement.
"A major shelling attack on Tuesday has left 18 civilians dead, including three children and two women, a pregnant one and an elderly one," according to the Observatory.
The attack targeted the majority-Kurdish neighbourhood of Sheikh Maqsud, where some 50,000 residents are caught in the crossfire of regime-held districts and those controlled by rebels.
Rebels including Ahrar al-Sham, which is allied to Al-Qaeda in Syria, kept up today their shelling of Sheikh Maqsud which overlooks regime-held areas, said the Observatory.
More From This Section
Abdel Rahman said the rebels want to take the neighbourhood because it would allow them to have "a launching pad for attacks" on government forces.
Aleppo became a divided city in 2012 after a rebel onslaught was met with resistance by the army.
Kurds represent about 15 per cent of Syria's population and have tried to avoid confrontation with the regime or non- jihadist rebels since war broke out in 2011.
On March 17, Kurdish parties, including the powerful Democratic Union Party (PYD) and their allies, announced the creation of a "federal system" in northern Syria.
The announcement was heavily criticised by Syria's opposition, who have vowed to use "all the political and military force" at their disposal to fight it.
Syria's conflict erupted in March 2011 with anti- government protests but has since morphed into a multi-front war drawing in regional powers.