Obama said prosecuting recreational users of marijuana in states that legalized the substance won't be a "top priority" in the fight against drug use, ABC News reported Friday.
"We've got bigger fish to fry," Obama said in an interview. "It would not make sense for us to see a top priority as going after recreational users in states that have determined that it's legal."
The federal government has a similar approach in the states where medicinal marijuana is legal.
Obama said he doesn't support widespread legalization of marijuana right now.
"This is a tough problem because Congress has not yet changed the law," Obama said. "I head up the executive branch; we're supposed to be carrying out laws. And so what we're going to need to have is a conversation ... how do you reconcile a federal law that still says marijuana is a federal offense and state laws that say that it's legal?"
On Election Day, Colorado and Washington voters approved measures that legalize the recreational use and sale of small amounts of marijuana in their states.
Marijuana is classified under the Controlled Substances Act as a Schedule I narcotic, same as heroin and LSD.
The Justice Department has been asked to investigate legal issues surrounding conflicting state and federal laws, ABC News said.
"There are a number of issues that have to be considered, among them the impact that drug usage has on young people, [and] we have treaty obligations with nations outside the United States," Attorney General Eric Holder said Wednesday in reference to the review that has begun.
Obama told ABC he, as a politician, has opposed legalizing marijuana and downplayed what he wrote in his 1995 memoir, "Dreams from My Father," in which he said he smoked marijuana regularly with high school friends who formed a "club of disaffection."
"There are a bunch of things I did that I regret when I was a kid," Obama said. "My attitude is, substance abuse generally is not good for our kids, not good for our society. I want to discourage drug use."