The Pentagon said the attack involved fighter jets, bombers and Tomahawk cruise missiles fired from ships in the region.
Syria confirmed that the country had been informed of the strike before it took place.
IS militants have persecuted tens of thousands of Christians across Iraq and Syria as they continue to take over parts of both countries.
In some towns and cities, Christianity has completely disappeared as many have fled for their lives.
The US said the air strikes started at around 1.30am British time, and were conducted by America, Bahrain, Qatar, Saudi Arabia, Jordan and the United Arab Emirates.
President Barack Obama was being kept informed.
In recent weeks, the US has been increasing surveillance flights over Syria to gather more data about where IS fighters are working from.
Syrian Anglican priest Nadim Nassar told Premier's News Hour British military engagement in Syria is not the answer.
He said: "All that we hear is the rhetoric of war and violence and air strikes and arming this and arming that.
"Where is the British diplomacy to bring people together in dialogue?"
Hear more from him: