Obama announced his executive actions in a video message to those present at the "Our Ocean" conference hosted by the US State Department, which focused on sustainable fisheries, marine pollution, and ocean acidification.
"We've already shown that when we work together, we can protect our oceans for future generations. So let's redouble our efforts," Xinhua quoted Obama as saying in a statement.
The White House said the Obama administration is considering how to "expand protections near the Pacific Remote Islands Marine National Monument in the south-central Pacific Ocean, an area which contains some of the most pristine tropical marine environments in the world".
The administration will consider the input of fishermen, scientists, conservation experts, elected officials, and other stakeholders "before making decisions about the geographic scope and details", it added.
The Washington Post, however, reported that Obama is looking at expanding the Pacific Remote Islands Marine National Monument from almost 87,000 square miles (225,328 square km) to nearly 782,000 square miles (2.03 million square km) and that the plan will affect seven islands and atolls controlled by the US.
The US daily also said that the plan, led by Secretary of State John Kerry, is likely to spark a new political battle with Republicans over the scope of Obama's executive powers.
Obama also said he is directing Federal agencies to develop a comprehensive program aimed at deterring illegal fishing, addressing seafood fraud, and preventing illegally caught fish from entering the marketplace by increasing traceability and transparency.
US Secretary of State John Kerry Monday said the oceans are facing threats from over-fishing, pollution and acidification, and called for "a comprehensive, global strategy" to protect them, media reported Tuesday.
Kerry made the remarks while inaugurating a two-day international ocean conference hosted by the US Department of State, to discuss the danger to the oceans and concrete actions that should be taken.