The LCC said 148 people were killed nationwide, including 77 in Aleppo. Thirty of those were killed in Helwaniyeh, it said.
Activist accounts and videos cannot be independently confirmed because the regime has strictly limited independent reporting in the country.
The Observatory also said government forces advanced in the Aleppo neighborhoods of Salaheddine, Seif el-Dawleh, and Izaa after rebels withdrew from the areas under heavy shelling.
Aleppo - which had been relatively quiet for most of the 18-month-old revolt - has emerged as the main battleground in Syria's civil war, with both sides largely locked in a stalemate despite the superior firepower of President Bashar al-Assad's regime.
The uprising against Assad began in March 2011, when protests calling for political change were met by a violent government crackdown by government troops. Many in the opposition took up arms, and activists say more than 23,000 people have been killed. The government says more than 4,000 security officers are among the dead.
Syrian army forces also regained full control of one of their largest posts in Aleppo after pushing rebels out of a section they had seized late Friday. But fighting continued to rage outside the Hanano barracks, which house more than 2,000 soldiers near the center of the city, according to the Observatory and activists.
Aleppo activist Mohammed Saeed said rebels were able to free scores of detainees from the barracks.
In other violence, the Observatory reported intense fighting Saturday in the Palestinian refugee camp of Yarmouk in Damascus, which had been subjected to government shelling the day before.
When Syria's unrest began, the country's half-million Palestinians tried to stay on the sidelines. But in recent months, young Palestinian refugees - enraged by mounting violence and moved by Arab Spring calls for greater freedoms - have been taking to the streets and even joining the rebels.
Clashes also broke out in the Damascus suburbs as well as the northern province of Idlib, the southern province of Daraa, and central Hama and Homs. Some of the fiercest fighting was in the Damascus neighborhood of Tadamon, according to the Observatory and the LCC. The groups claimed an army helicopter had been shot down.
Earlier Saturday, a major water pipeline in Aleppo was damaged during the intense fighting, leaving several neighborhoods without drinking water.
The Syrian government and opposition traded blame.
"Water was completely cut from several neighborhoods in the city," Saeed said via Skype. "This will only increase the suffering of people."