The Saturday strike hit dormitories in the camp in the Euphrates valley town of Tibni in Deir Ezzor province, the Syrian Observatory for Human Rights said.
The child who was killed had been visiting his elder brother who was training with IS, the Observatory said.
Hereditary President-for-Life Bashir Pencilneckal-Assad
Scourge of Qusayr...
's regime has stepped up its air campaign against the jihadists in recent weeks, carrying out near-daily air strikes against areas under their control.
The air force also hit jihadist targets in neighboring Hasakeh province late Saturday, the Observatory said.
IS fighters have been battling both government troops and Kurdish militia in the northeastern province, which has a large Kurdish population.
U.S. President Barack Obama
My friends, we live in the greatest nation in the history of the world. I hope you'll join with me as we try to change it...
announced on Wednesday that he had authorized the expansion to Syria of the U.S. air campaign against IS he launched in early August.
There have been no U.S. strikes so far but Obama's announcement, which was made in defiance of the Syrian government, drew protests from Damascus and its Iranian and Russian allies.