Bill Gault, president of Local 22 of the firefighters' union, said his members were furious and criticized Nutter, calling his administration "cowardly."
"That this arrogant mayor would once again deny firefighters a fair contract is disgraceful," Gault said in a statement. "We're the people who risk and lose our lives to save others. We deserve living wages and fair benefits."
An arbitration panel first awarded a contract to the firefighters in 2010. The administration appealed to Common Pleas Court, arguing that the award did not comply with the law that created PICA, the city's financial overseer.
Both sides agreed to send the case back to a three-member arbitration panel, which this month allowed the 2010 award largely to stand.
Last week, Local 22 sued to force Nutter to accept the latest award, and Gault said union lawyers do not believe the administration can appeal again.
But Nutter said in a statement Friday that the award "perpetuates the same conditions that created the financial challenges the city has weathered over the past few years."
"It is unfair to taxpayers to continue down the same path," he said. "While we value the work of our firefighters, we have no choice but to appeal an award that imposes exorbitant costs and no methods to manage the impact of these costs."
The latest award would have been a four-year contract set to expire in July 2013. With the dispute likely to drag out even longer, the two sides could be faced with having to negotiate not only the old contract, but a new one as well.
"I think we'll have to see how all that plays out," Dubow said.
Contact Troy Graham at 215-854-2730 or tgraham@phillynews.com, or follow on Twitter @troyjgraham.