The Israeli attack targeted an area "near rockets depots belonging to Lebanese group Hezbollah", said the UK-based Syrian Observatory for Human Rights, which has an extensive network of sources in Syria.
"At least 36 soldiers were killed and dozens wounded," it said.
Syrian state news agency SANA said the pre-dawn strike killed and wounded civilians as well as military personnel.
A Syrian military source told SANA that "at approximately 1:45 am, the Israeli enemy launched an air attack from the direction of Athriya, southeast of Aleppo", adding that "civilians and military personnel" had been killed and wounded in the strike.
Contacted by AFP from Jerusalem, the Israeli military said it would "not comment on reports in the foreign media".
Israel has launched hundreds of air strikes on targets in Syria since civil war broke out in 2011, mainly targeting Iran-backed forces including militants from Lebanon's Hezbollah movement as well as Syrian army positions.
The strikes have increased since Israel's war with Palestinian militant group Hamas, a Hezbollah ally, began on October 7.