Calling for a greater partnership with the Islamic world in an address to the Turkish parliament, Mr. Obama called the country an important U.S. ally in many areas, including the fight against terrorism. He devoted much of his speech to urging a greater bond between Americans and Muslims, portraying terrorist groups such as al Qaida as extremists who did not represent the vast majority of Muslims.
"Let me say this as clearly as I can," Mr. Obama said. "The United States is not and never will be at war with Islam. In fact, our partnership with the Muslim world is critical ... in rolling back a fringe ideology that people of all faiths reject."
The U.S. president is trying to mend fences with a Muslim world that felt it had been blamed by America for the Sept. 11, 2001, terrorist attacks.
Al Jazeera and Al Arabiyia, two of the biggest Arabic satellite channels, carried Mr. Obama's speech live.
"America's relationship with the Muslim world cannot and will not be based on opposition to al Qaida," he said. "We seek broad engagement based upon mutual interests and mutual respect."
"We will convey our deep appreciation for the Islamic faith, which has done so much over so many centuries to shape the world for the better, including my own country," Mr. Obama said.
The president also said, to a round of applause, that the United States supports becoming a member of the European Union.
Joining President Abdullah Gul at a news conference after talks in Ankara, Mr. Obama said earlier he wanted to build on "what is already a strong foundation" with Turkey. He said relations between the two countries have for too long been defined on mostly military and national security terms but that they must also work together on the global economic crisis.
Mr. Obama said he and Gul have been "very clear that terrorism is not acceptable under any circumstances." He also said Turkey and the United States can build a "model partnership" between a predominantly Christian nation and a predominantly Muslim nation.
President Obama paid tribute to the memory of modern Turkey's founding father on Monday as he reached out for help to wind down the war in Iraq and bring stability to the Middle East.
He is also counting on the only major predominantly Islamic member of NATO to remain a steadfast ally in the conflict. Turkey has diplomatic leverage with both and Afghanistan.
"I'm honored to pay tribute to his name," Mr. Obama said at wreath-laying ceremony during a morning visit to the tomb of Mustafa Kemal Ataturk.
The tomb is a large limestone, columned complex on the top of a high hill with a dramatic view of Turkey's capital city.
Mr. Obama stood at a podium and wrote in a guest book for nearly four minutes.
Mr. Obama's visit is being closely watched by an Islamic world that harbored deep distrust of his predecessor.
"The President is already popular here just because he is not George Bush," reports CBS News senior White House correspondent Bill Plante.
Bulent Aliriza, from the Center for Strategic and International Studies, told Plante, "Turks seem to identify with somebody who has a different background who they hope will be conducting a different foreign policy, will be determining a different approach to fighting terrorism, different from that of George Bush."
Minnesota Rep. Keith Ellison, the first Muslim to be elected into the U.S. Congress, host Bob Schieffer, "The Muslim world has always looked at the United States as a country where freedom and Democracy abound, and they'd like to have some of it," Ellison added.
Mr. Obama was spending two days in Turkey as he wraps up an event-packed, eight-day international trip that included stops in Britain, France, Germany and the Czech Republic.
A day-by-day guide to one of the most closely watched presidential trips in recent memory.
The president arrived in Ankara late Sunday. He was to meet with Turkish leaders and speak to parliament, then go on to Istanbul for events on Tuesday.
In his inaugural address in January, Obama pledged to reach out to the Muslim world.
At a luncheon Sunday for leaders of the European Union's 27 nations in Prague, he said the West should seek greater cooperation and closer ties with Islamic nations. He suggested one way was by allowing Turkey to join the European Union - a contentious subject for some European countries. French President Nicolas Sarkozy said after Mr. Obama's remarks that the decision was the EU's to make, not Washington's.
Americans remain unsure of what to make of Islam even as most people in the U.S. think Mr. bama should seek better relations with the Muslim world, according to a Washington Post-ABC News poll. About 55 percent of Americans say they lack a good, basic understanding of the religion, the poll found, and 48 percent have an unfavorable view of it.
Mr. Obama's trip to Turkey, his final scheduled country visit, ties together themes of earlier stops. He attended the Group of 20 economic summit in London, celebrated NATO's 60th anniversary in Strasbourg, France, and on Saturday visited the Czech Republic, which included a summit of European Union leaders in Prague.
Turkey is a member of both the G-20 and NATO and is trying to get into the EU with the help of the U.S.
Turkey has the largest army in NATO after the United States. It and tiny Albania, recently admitted, are the only predominantly Muslim members of NATO.
Turkey opposed the war in Iraq in 2003 and U.S. forces were not allowed to go through Turkey to attack Iraq. Now, however, since Mr. Obama is withdrawing troops, Turkey has become more cooperative. It is going to be a key country after the U.S. withdrawal in maintaining stability, although it has long had problems with Kurdish militants in north Iraq.
Turkey maintains a small military force in Afghanistan, part of the NATO contingent working with U.S. troops to beat back the resurgent Taliban and deny al Qaeda a safe haven along the largely lawless territory that straddles Afghanistan's border with Pakistan. Turkey's participation carries enormous symbolic importance to the Muslim world because of its presence in the fight against Islamic extremism. Albania, one of the poorest nations in Europe, has a small contingent in Afghanistan.