During the trail, a court heard the two killers were “under the influence of nitrous oxide” when they chased Harley along King’s Mill Lane and then “brutally “attacked him with knives.
In a statement the AGO said Robert Coutts, the Solicitor General for England and Wales, had ruled the jail terms would not be reviewed.
A spokesperson said: “The Solicitor General was shocked by this case and wishes to express his sympathies to Harley Brown’s family.
“After careful consideration the Solicitor General has concluded that this case cannot properly be referred to the Court of Appeal.”
The spokesperson said a referral could only be made if a sentence is “unduly lenient” and limited to circumstances where a judge has made a “gross error” or imposed a term “outside the range of sentences reasonably available”.
They added: “The threshold is a high one, and the test was not met in this case.”
