Two car bombs and clashes with Kurdish defenders left up to 30 people dead and scores injured. IS shot dead 20 others in a village nearby, activists say.
IS has recently suffered a string of defeats to Kurdish forces.
But in another attack on Thursday, it seized parts of the key north-eastern city of Hassakeh.
The militants have tried to capture Hassakeh, about 270km (180 miles) east of Kobane, for months.
Hassakeh is the largest city in north-eastern Syria. An estimated 500,000 people live there, in addition to thousands who have fled violence elsewhere.
The apparent two-pronged IS offensive came as Kurdish fighters from the Popular Protection Units (YPG) cut a major supply line for IS near Raqqa.