Women and children were among those who died overnight in the village of al-Baruda, the UK-based Syrian Observatory for Human Rights reported.
Anti-IS group Raqqa is Being Slaughtered Silently said many were displaced residents of Homs province.
The coalition said an assessment team was examining the reports.
Its warplanes are conducting strikes against IS targets in support of an alliance of Arab and Kurdish militias that is preparing to launch an assault on Raqqa.
Syrian Democratic Forces (SDF) fighters are only 3km (2 miles) from the eastern edge of the city, which is de facto capital of the caliphate proclaimed by IS in 2014.
The Observatory, which monitors the conflict in Syria via a network of sources on the ground, said coalition aircraft bombed al-Baruda, about 15km (10 miles) west of Raqqa, early on Wednesday.
Those killed included a woman and her five children, as well as three couples, while a number of other people were in a critical condition, it added.
Raqqa is Being Slaughtered Silently said most of them had been sheltering in the village after fleeing fighting between IS militants and Syrian government forces near al-Sukhna, a town about 120km (75 miles) to the south in Homs province.
The reported attack came after the Observatory reported that 225 civilians had been killed in coalition air strikes between 23 April and 23 May.
The coalition, which says it takes all reasonable precautions to reduce the risk of harm to civilians, insists the figure is far lower.
Late last month, the coalition assessed that its 20,200 air strikes in Syria and neighbouring Iraq had "unintentionally" killed at least 352 civilians since 2014.
In a separate development on Wednesday, Syrian state media reported that the overall IS military commander, or "minister of war", in Syria had been killed.
A military source identified him as Abu Musab al-Masri and said he was one of 13 senior figures from the jihadist group to have died during recent army operations east of the second city of Aleppo.
At least 16 civilians have been killed in a US-led coalition air strike near so-called Islamic State's Syrian stronghold of Raqqa, activists say.