A Pentagon statement said two F/A-18 warplanes dropped 225 kilograms of laser-guided bombs on a mobile artillery piece which "(the ISIL) was using... to shell Kurdish forces defending Erbil where US personnel are located."
Later on Friday, the US military said it had conducted two additional air strikes to help defend the city where US personnel are assisting the government of Iraq.
"A remotely piloted aircraft struck a terrorist mortar position. When ISIL fighters returned to the site moments later, the terrorists were attacked again and successfully eliminated," the Pentagon said.
According to the statement, in the third attack, four F/A-18 aircraft successfully struck a stationary ISIL convoy of seven vehicles and a mortar position near Erbil.
"The aircraft executed two planned passes. On both runs, each aircraft dropped one laser-guided bomb making a total of eight bombs dropped on target neutralizing the mortar and convoy," the Pentagon said.
"Fighters have captured US-made weapons as Kurdish troops withdrew from various regions. Washington also wants to address that,"Al Jazeera’s reporter from Erbil said.
US President Barack Obama had on Thursday authorized air strikes against ISIL fighters in Iraq, who have taken over areas of the country, saying the measure was meant to avert "genocide".