"Our position - based on long-standing Supreme Court precedent - is that US courts have no jurisdiction over non-US citizens being held in military custody abroad," White House spokesman Scott McClellan said.
"There is 50-year-old-Supreme Court precedent in the case of Germans, prisoners of war, held in China," he said, adding that it held that US courts had no jurisdiction in that matter.
The San Francisco-based appeals court issued its ruling on Thursday in a case filed by Belaid Gherebi on behalf of his brother, Faren, a Libyan who is being held without charge at Guantanamo along with hundreds of other men captured in the US "war on terror".
The court was harshly critical of the detention of the prisoners at Guantanamo without charge or the protections of the Geneva Convention.
"Let's keep in mind that we are talking about enemy combatants who were involved in harming American citizens," McClellan said.
"Let's keep in mind that we are talking about enemy combatants who were involved in harming American citizens"
spokesman, White House
The more than 650 Guantanamo inmates have not been charged with any crime. A few have been released over the past year.
The 2-1 ruling delivered by the San Francisco-based US Court of Appeals for the Ninth Circuit was the second blow delivered on Thursday to legal manoeuvres by the administration of President George Bush in its "war on terror".
Earlier in the day, a federal appeals court in New York ruled that Bush did not have the right to detain Jose Padilla, a US citizen seized on US soil, as an "enemy combatant" and ordered his release within 30 days.