The publication, timed to coincide with International Human Rights Day, accuses Syrian government forces of carrying out "at least 20 massacres that involved the slaughter of 2,885 people" with knives and other crude weapons.
The victims, the report said, include "more than 200 children and 120 women."
The Coalition said the killings amounted to "a series of organised crimes of genocide."
It said the 81-page report was based on open source reporting, investigations by international organisations and the testimony of both survivors and opposition activists.
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The United Nations concluded that the majority of those killed in the incident were summarily executed, and local residents said the attack was carried out by pro-regime militias.
The report also noted dozens of deaths in the city of Banias and the village of Bayda nearly a year later, many of them summary executions of women and children.
"The regime began in the early days of the revolution to establish death squads specifically to carry out massacres with 'cold arms,'" the Coalition said, using a term for weapons that do not use fire or explosions.