The airstrikes reportedly destroyed two tanks controlled by the Islamist forces.
U.S. Central Command has now launched 123 airstrikes in Iraq.
It was not clear whether they were U.S. or Iraqi airstrikes.
The lawmaker pushed back on the assertion raised by Sen. Tim Kaine (D-Va.) a day earlier.
Obama said operations authorized in Iraq would protect refugees trapped on Sinjar Mountain.
David Cameron on Friday welcomed President Obama's authorization of targeted airstrikes.
He continues to choose missiles over manpower when fighting enemies abroad.
Support for strikes jumped 9 points, but Obama's Iraq approval remains at 42 percent.
More than six in 10 voters approve of U.S. airstrikes in Iraq.
The president said U.S. forces are beating back “barbaric terrorists.”
U.S. forces have conducted four more airstrikes against Islamic militants in Iraq.