Boats have also been banned from sailing near the coastline at the hotel's location.
Thousands of police are to be deployed in Athens for draconian security measures during a two-day visit to Athens by President Bar. Clinton's visit, which came during the height of US intervention in the wars ensuing from the breakup of Yugoslavia, was marked with extensive violent demonstrations.
There is a strong anti-American tradition among Greek left-wingers who still resent USA support for Greece's 1967-74 military dictatorship.
As is usual in Athens, Greek anarchists, far-left groups and trade unions have called for protests against the visiting USA leader, despite a two-day ban on public gatherings in central Athens.
At the time of the protests, Obama was dining at the presidential palace alongside Tsirpas and Greek President Prokopis Pavlopoulos.
Some 2,500 people brandishing banners denouncing United States imperialism and claiming "Obama non grata", or not welcome, were blocked from heading toward the site where Obama was meeting Greek Prime Minister Alexis Tsipras. Pavlopoulos will host an official dinner for Obama at the presidential mansion in the evening.
President Obama is on his last European tour and is making a push for strong democracies. Trump also criticized a proposed US-EU free trade agreement called the Transatlantic Trade and Investment Partnership (TTIP), blaming similar economic pacts like NAFTA for job losses in his homeland.
"Let me point out that it was one thing that we knew about Donald Trump when he was seeking to become the candidate for the Republican Party, another thing during the election period, and now that he is the President-elect, and it's quite another when he will be the president of a country that is a major player, a global player", Tsipras said.
Greece's government has hailed Mr Obama's visit as being of "huge importance" for Greece and Europe.
Issues to be discussed with Greek leaders include the country's debt crisis and the refugee situation.
President Obama complained on Tuesday how hard it has been for him to work with Congress during his final foreign trip in the White House.
He also pledged support for Greece's economy, as Greek leaders seek a fresh U.S. pledge to help alleviate the country's enormous public debt, a measure actively sought by the International Monetary Fund but opposed by leading European lender Germany.
Athens signed up to a third economic bailout package of up to 86 billion euros (74.79 billion pounds) in mid-2015 but says it needs a long-term debt restructuring to exit the crisis - a message repeated on Tuesday by Tsipras, a leftist whose popularity is waning.
Greek riot police meanwhile used tear gas and stun grenades in central Athens Tuesday to disperse about 3,000 left-wing marchers protesting a visit by Obama, after they tried to enter an area declared off-limits to demonstrators.
Paying the first presidential visit to Greece since Bill Clinton in 1999, Obama sought to reassure North Atlantic Treaty Organisation allies that Trump, despite belittling the alliance during the campaign, wouldnt abandon it. Obama said Democratic and Republican administrations had respected North Atlantic Treaty Organisation and predicted significant continuity even as we see a transition in government.. "Because societies which are able to unify ourselves around values and ideals and character, and how we treat each other, and cooperation and innovation, ultimately are going to be more successful than societies that don't".
The U.S. has praised Greek efforts to overhaul its economy but has repeatedly stressed the country must continue with painful reforms. "A suspicion of globalization, a desire to rein in its excesses", Obama said. A reluctance by many other European Union countries to host refugees has left more than 60,000 people stranded in Greece, many living in poor conditions in massively overcrowded camps dotted across the country.
Rights organizations have urged Obama to use his visit to highlight these people's plight and Europe's response to the crisis.
His comments come after last week's election, in which 209 out of 700 counties across that USA that had twice voted for Obama in presidential elections flipped this time and voted for the Republican candidate, Donald Trump.
Mr. Obama is due to meet German Chancellor Angela Merkel and other major European leaders in Berlin this week, for discussions expected to focus on economics, security, and rising populism.