Gibbs told reporters first lady Michelle Obama had a hand in the process. Earlier in the day, the first lady said the president had been smoke-free for nearly a year.
Gibbs sparked laughter among reporters when he responded to a question on what had helped the president to quit.
"I don't doubt that the first lady …," Gibbs began before he was interrupted. "No, no, I don't mean that in a funny way."
Obama, who began smoking as a teenager, had promised his wife he would quit smoking if she let him run for president.
"I think that when somebody decides -- I think when somebody decides to quit smoking, to try to overcome the physical addiction that they have, they do it not just because they want to, but because others want them to and because others around them give them the type of encouragement that they need to break what is -- what is a tough habit to break," Gibbs said.
The president's day Tuesday was filled with non-public meetings, including a session with Senate Minority Leader Mitch McConnell, R-Ky. Gibbs had no information on what was said.
In the morning, Obama received the daily briefings, his schedule indicated.
National Policy Alliance, a think tank focused on issues of concern to the African-American community, was on the afternoon agenda, followed by a meeting with Vice President Joe Biden and Defense Secretary Robert Gates.