In a letter to House Speaker John Boehner, R-Ohio, Obama said U.S. forces "provided limited technical support to the French forces in that operation, but took no direct part in the assault on the compound where it was believed the French citizen was being held hostage."
"United States combat aircraft briefly entered Somali airspace to support the rescue operation, if needed," the U.S. president said. "These aircraft did not employ weapons during the operation.
"I directed U.S. forces to support this rescue operation in furtherance of U.S. national security interests, and pursuant to my constitutional authority to conduct U.S. foreign relations and as commander in chief and chief executive."
Obama cited his authority "consistent with the War Powers Resolution," and said his notice to the speaker was part of his effort to keep Congress apprised of U.S. military actions.
French Defense Minister Jean-Yves Le Drian said al-Shabaab's militant response with heavy weapons during the Friday attempt to rescue French secret service agent Denis Allex came as a surprise.
Two French soldiers and 17 insurgents died in the effort to free Allex, Euronews.net reported Sunday.
"We underestimated that," he said.
Le Drian said Allex was killed by his captors. Al-Shabaab said the hostage was alive, but had been moved to a new location and his fate would be decided within the next two days.
Allex has been held in what France said was inhumane conditions since his capture in Mogadishu in July 2009.
A French soldier was killed in the rescue mission, but his body was left behind after two attempts to retrieve the remains failed, a resident said.
A second soldier also died in the mission, Euronews.net reported, though the insurgents said he was wounded and was now "in the custody of the mujahideen," CNN reported.