The Britain-based monitor said the attack on the village in the northeast of the province came early on Wednesday, with violent clashes breaking out after the jihadists tried to storm the area.
"National Defence Forces and other pro-regime militias battled IS fighters with each side shelling the other," said the Observatory.
"At least 19 Islamic State members were killed... along with three National Defence Force fighters, and six people were wounded, including a child and two women."
Jub al-Jarah lies northwest of the ancient city of Palmyra, which was captured by IS on May 21, and the group is also to the west of the village, in neighbouring Homs province.
Its residents, like President Bashar al-Assad, mostly belong to the Alawite sect, an offshoot of Shiite Islam that IS considers heretical.
On Tuesday night, two IS suicide bombers killed 10 Syrian soldiers in the northeastern city of Hasakeh.
"Ten soldiers were killed and 16 others injured in two suicide attacks carried out by IS against army positions in Hasakeh," the Observatory said.
"The first attack was carried out by three jihadists against a military barracks in the centre of town, while the second was carried out by one suicide bomber against a checkpoint near a children's hospital."
A third suicide bomber hit a post manned by the Kurdish security forces in the city, causing serious damage to buildings in the area but no deaths.
Control of Hasakeh, which is ethnically mixed, is divided between Syrian troops and Kurdish forces.
On May 30, IS launched a bid to enter the city, but was pushed back after violent clashes with Syrian troops and Kurdish fighters.
Also Tuesday night, at least 13 civilians were killed in a car bomb attack against a mosque in a village near the capital Damascus, the monitor said.
The bomb exploded in the village of Al-Tall as worshippers were leaving prayers.
State news agency SANA reported the "terrorist" blast that targeted the mosque, but gave no precise toll.
It was not immediately clear who was behind the attack in the town, which lies just north of the capital, where a truce is in place between rebel forces inside and regime troops outside.
More than 230,000 people have been killed in Syria since the conflict began with anti-government protests before spiralling into a war after a regime crackdown.
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"National Defence Forces and other pro-regime militias battled IS fighters with each side shelling the other," said the Observatory.
"At least 19 Islamic State members were killed... along with three National Defence Force fighters, and six people were wounded, including a child and two women."
Jub al-Jarah lies northwest of the ancient city of Palmyra, which was captured by IS on May 21, and the group is also to the west of the village, in neighbouring Homs province.
Its residents, like President Bashar al-Assad, mostly belong to the Alawite sect, an offshoot of Shiite Islam that IS considers heretical.
On Tuesday night, two IS suicide bombers killed 10 Syrian soldiers in the northeastern city of Hasakeh.
"Ten soldiers were killed and 16 others injured in two suicide attacks carried out by IS against army positions in Hasakeh," the Observatory said.
"The first attack was carried out by three jihadists against a military barracks in the centre of town, while the second was carried out by one suicide bomber against a checkpoint near a children's hospital."
A third suicide bomber hit a post manned by the Kurdish security forces in the city, causing serious damage to buildings in the area but no deaths.
Control of Hasakeh, which is ethnically mixed, is divided between Syrian troops and Kurdish forces.
On May 30, IS launched a bid to enter the city, but was pushed back after violent clashes with Syrian troops and Kurdish fighters.
Also Tuesday night, at least 13 civilians were killed in a car bomb attack against a mosque in a village near the capital Damascus, the monitor said.
The bomb exploded in the village of Al-Tall as worshippers were leaving prayers.
State news agency SANA reported the "terrorist" blast that targeted the mosque, but gave no precise toll.
It was not immediately clear who was behind the attack in the town, which lies just north of the capital, where a truce is in place between rebel forces inside and regime troops outside.
More than 230,000 people have been killed in Syria since the conflict began with anti-government protests before spiralling into a war after a regime crackdown.
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