ISIS attacked a village near the main road between Aleppo and Homs on Thursday, killing many residents, Syrian state media and a war monitor said.
The militant group said in a social media feed it had captured the village of Aqarib al-Safi, but the government-run SANA news agency reported that the attack had been repulsed.
SANA said ISIS fighters had killed 20 people in the village before the army and allied militia drove them away. The Syrian Observatory for Human Rights reported that clashes were still going on there and in the village of al-Saboura.
The Observatory said that at least 31 people, including both civilians and fighters on both sides, had been killed and that dozens had been injured. It said that some of those killed had first been taken prisoner by ISIS.
The villages are north of al-Salamiya close to the only road still useable between Aleppo and other parts of Syria held by the government.
The army and its allies hold the road and a small strip of land on each side, with ISIS controlling the eastern area and Syrian rebel groups, including hardline Islamists, the western area.
The Observatory said the attack was the most violent so far this year by ISIS on the road