WASHINGTON — Hoping to cement a major element of his foreign policy legacy, President Barack Obama on Friday lifted additional restrictions on U.S. trade and travel with Cuba, including an end to strict limits on the Cuban rum and cigars an American visitor can take home.

The measures mark the latest steps by the Obama administration to restore diplomatic and economic ties with the island nation after more than half a century of hostility. Obama and President Raul Castro announced the diplomatic opening on Dec. 17, 2014.

Susan Rice, Obama’s national security adviser, said the administration has gone as far it can to normalize relations while a U.S. trade embargo stays in place.

Only Congress can lift the trade embargo, which was imposed in 1960 against Cuba’s then-new communist government. Washington severed diplomatic ties with Havana the following year.

Rice urged Congress to end the embargo, but that is unlikely given opposition from several powerful Republicans.

“Congress must do its part; we must lift the embargo once and for all,” Rice said at the Wilson Center, a nonpartisan think tank in Washington. “End this outdated burden on the Cuban people.”

Rice said the new measures, which Obama announced in a special presidential directive, will benefit both Americans and Cubans, even though most revenue generated by tourism in Cuba ends up in government hands.

Administration officials said the White House was using the new rules to expand and solidify its opening to Cuba, especially before a different administration takes shape.

“It would be profoundly unwise and counterproductive to turn back the clock,” Rice said when asked if a future president could tear up the deal.

Rice also urged Congress to confirm Obama’s nomination of Jeffrey DeLaurentis as U.S. ambassador to Cuba. DeLaurentis is a career diplomat who is already chief of mission in Havana.

Rice noted that Friday was the 54th anniversary of the start of the Cuban Missile Crisis, when the world teetered on the brink of nuclear war after the John F. Kennedy administration discovered Soviet nuclear-tipped missiles in Cuba and announced a naval embargo in 1962.

Among the changes, the new regulations lift the cap on how much alcohol, tobacco and other Cuban merchandise an American visitor can take home.

Until now, a U.S. citizen could import only $100 worth of alcohol and tobacco. Now the same duties used for other countries will apply to Cuban products brought home “for personal use.”

The new rules also make it easier for U.S. and Cuban researchers to conduct joint medical investigations and for Cuba to sell approved pharmaceutical products in the U.S. market.

In addition, cargo ships will be allowed to dock at U.S. ports directly after visiting Cuba, ending a 180-day ban between those ports of call.

“Basically they are consolidating what they have already done, making it more difficult to undo,” said Geoff Thale, program director for the Washington Office on Latin America, an independent research and advocacy group.

In a statement, Obama said “challenges remain” in U.S. dealings with Cuba, primarily on Havana’s poor record on human rights and democracy. But Obama said “engagement” is the best method to address the differences.