During a speech on Friday at the Office of the Director of National Intelligence to mark its 10th anniversary, Obama praised the US Intelligence Community, calling it the most capable in the world.
"We all grieve when any innocent life is taken,” Obama told a couple of hundred intelligence officials gathered in an auditorium at the sprawling gray office building in Mclean, Virginia, just outside of Washington.
"We don't take this work lightly. And I know that each and every one of you understand the magnitude of what we do and the stakes involved and these aren't abstractions and we're not cavalier about what we do," he added.
The president also promised a review aimed at preventing future mistakes, a day after the White House revealed intelligence failure that caused the death of the two hostages.
American Warren Weinstein and Italian Giovanni Lo Porto were accidentally killed in January during a CIA drone strike against an al-Qaeda compound in Pakistan.
The intelligence that directed the drone strike turned out to have been tragically incorrect, US officials and lawmakers said Thursday.
Obama, who has expanded the use of US drones, expressed his deep regrets Thursday and apologized on behalf of the US government for the death of 73-year-old Weinstein and 39-year-old Lo Porto.
Their deaths have created the biggest crisis yet for the Obama administration’s controversial program--a central part of US "counterterrorism strategy” which has provoked a strong backlash in the countries where drones have been used, from Pakistan to Yemen.
Critics say the incident highlights the troubling reality about the secret drone attacks that often result in civilian casualties because of the uncertainties about who is being targeted.
"These new disclosures raise troubling questions about the reliability of the intelligence that the government is using to justify drone strikes,” Jameel Jaffer, deputy legal director of the American Civil Liberties Union (ACLU) said Thursday.
"In each of the operations acknowledged today, the US quite literally didn’t know who it was killing,” he added.
Over 2,000 people have been killed in US drone strikes in Pakistan alone, according to official figures from Islamabad.