The raids also for the first time targeted the Ahrar al-Sham rebel group, an Islamist brigade that is part of a key armed opposition front.
The strikes against Al-Qaeda affiliate Al-Nusra Front in northwestern Syria killed several jihadists as well as two children, the Britain-based Syrian Observatory for Human Rights said.
Coalition aircraft carried out "several raids after midnight" targeting an Al-Nusra vehicle and one of its positions, the Observatory said.
The Observatory also said today that the coalition had carried out strikes for the first time against Ahrar al-Sham, near the Turkish border.
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The group is one of Syria's largest armed opposition groups and is part of the key Islamic Front coalition of Islamist rebels.
It is believed to have between 10,000 and 20,000 fighters and espouses a conservative ideology, though it has not expressed the same transnational jihadist aspirations as Al-Nusra or the Islamic State group.
The reported raids are a new blow for Ahrar, which saw 47 members of its leadership killed in a blast in Idlib province in the northwest last month.
No group claimed responsibility for the attack, which wiped out most of Ahrar's senior religious and military chiefs, and it did not point the finger at anyone.
US and Arab nations have been carrying out air strikes against IS in Syria since September 23 in a bid to prevent the jihadist group from seizing more territory in the conflict-hit nation.
There have been no reported strikes on groups outside IS since, but this second attack comes after Al-Nusra made gains against Western-backed rebel fighters in the Idlib region.