Sandra Hyde, whose son Ben was killed in a mob attack in Iraq, believed the report would be a "whitewash".
The radical Islamist group published the reaction to the historic vote in a propaganda magazine.
One staff member was hit by flaming bottle and police are investigating racial hate motive.
The decision by British voters to leave the EU is unlikely to be the last anti-establishment uprising in the West.
David Cameron started laying the groundwork for his successor Monday.
The British PM is stepping down, but he will not have an easy summer.
Britain's vote to leave the EU has left many wondering what the next steps will be.
Senior Conservatives issue letter calling for Cameron to stay as PM regardless of referendum outcome.
The outcome of the landmark referendum may not be known until the late morning hours of Friday.
The vote comes after a bitter campaign that appeared to divide the nation down the middle.
Divorce or not, Europe will continue to have a huge influence over Britain.
The number of firearms offenses has fallen from a high of 24,094 in 2004 to 7,866 in 2015.