Attorney General Jeff Sessions has claimed legal cannabis causes violent crime, despite a lack of evidence for his claim.
Mr Sessions said the Justice Department will try to adopt "responsible policies" for enforcement of federal anti-marijuana laws.
He added that he believes violence surrounds the sale and use of the drug in the US.
“I believe it’s an unhealthy practice, and current levels of THC in marijuana are very high compared to what they were a few years ago, and we’re seeing real violence around that,” the attorney general said.
“Experts are telling me there’s more violence around marijuana than one would think and there’s big money involved."
While stopping short of saying what he would do, Mr Sessions said he doesn't think America will be a better place with "more people smoking pot."
"I am definitely not a fan of expanded use of marijuana," he added. "But states, they can pass the laws they choose. I would just say, it does remain a violation of federal law to distribute marijuana throughout any place in the United States, whether a state legalises it or not."
Studies have found no correlation between the legalisation of marijuana and violent crime rates.
However, law enforcement officials in states such as Colorado say drug traffickers have taken advantage of lax marijuana laws to hide in plain sight, illegally growing and shipping the drug across state lines, where it can sell for much higher.
Pot advocates say officials have exaggerated the problem.
"You can't sue somebody for a drug debt," Mr Sessions said. "The only way to get your money is through strong-arm tactics, and violence tends to follow that."
His comments were in keeping with remarks made last week by White House spokesman Sean Spicer, who said the Justice Department would step up enforcement of federal law against recreational marijuana.
Eight states and the District of Columbia have legalised marijuana for recreational use.
The controversial orders Donald Trump has already issued
The controversial orders Donald Trump has already issued
1/9 Trump and the media
White House Press Secretary Sean Spicer takes questions during the daily press briefing
2/9 Trump and the Trans-Pacific Partnership
Union leaders applaud US President Donald Trump for signing an executive order withdrawing the US from the Trans-Pacific Partnership negotiations during a meeting in the Roosevelt Room of the White House in Washington DC. Mr Trump issued a presidential memorandum in January announcing that the US would withdraw from the trade deal
3/9 Trump and the Mexico wall
A US Border Patrol vehicle sits waiting for illegal immigrants at a fence opening near the US-Mexico border near McAllen, Texas. The number of incoming immigrants has surged ahead of the upcoming Presidential inauguration of Donald Trump, who has pledged to build a wall along the US-Mexico border. A signature campaign promise, Mr Trump outlined his intention to build a border wall on the US-Mexico border days after taking office
4/9 Trump and abortion
US President Donald Trump signs an executive order as Chief of Staff Reince Priebus looks on in the Oval Office of the White House. Mr Trump reinstated a ban on American financial aide being granted to non-governmental organizations that provide abortion counseling, provide abortion referrals, or advocate for abortion access outside of the United States
5/9 Trump and the Dakota Access pipeline
Opponents of the Keystone XL and Dakota Access pipelines hold a rally as they protest US President Donald Trump's executive orders advancing their construction, at Columbus Circle in New York. US President Donald Trump signed executive orders reviving the construction of two controversial oil pipelines, but said the projects would be subject to renegotiation
6/9 Trump and 'Obamacare'
Nancy Pelosi who is the minority leader of the House of Representatives speaks beside House Democrats at an event to protect the Affordable Care Act in Los Angeles, California. US President Donald Trump's effort to make good on his campaign promise to repeal and replace the healthcare law failed when Republicans failed to get enough votes. Mr Trump has promised to revisit the matter
7/9 Donald Trump and 'sanctuary cities'
US President Donald Trump signed an executive order in January threatening to pull funding for so-called "sanctuary cities" if they do not comply with federal immigration law
8/9 Trump and the travel ban
US President Donald Trump has attempted twice to restrict travel into the United States from several predominantly Muslim countries. The first attempt, in February, was met with swift opposition from protesters who flocked to airports around the country. That travel ban was later blocked by the Ninth Circuit Court of Appeals. The second ban was blocked by a federal judge a day before it was scheduled to be implemented in mid-March
SANDY HUFFAKER/AFP/Getty Images
9/9 Trump and climate change
US President Donald Trump sought to dismantle several of his predecessor's actions on climate change in March. His order instructed the Environmental Protection Agency to reevaluate the Clean Power Plan, which would cap power plant emissions
The Justice Department has several options available should it decide to enforce the federal law, including filing lawsuits on the grounds that state laws regulating pot are unconstitutional because they are pre-empted by federal law.
Mr Sessions said he met with Nebraska's attorney general, who sued Colorado for allegedly not keeping marijuana within its borders.
The lawsuit was dismissed by the US Supreme Court, but neighbouring states continue to gripe that Colorado and other pot-legal states have not done enough to keep the drug from crossing their borders.Reuse content