Standing alongside German Chancellor Gerhard Schroeder, a harsh critic of the U.S.-led war in Iraq, Rice urged the world community to show support for "the people of Iraq who, on Sunday demonstrated they are prepared to set aside fear and their past and try to build a new and free society."
Berlin was her second stop on a weeklong tour of Europe and the Middle East.
"Now is the time for our diplomacy to put our alliance to work in the service of great goals and great opportunities that stand before us," she said.
Earlier, in London, Rice responded to a reporter's question about the possibility of a U.S. attack on Iran. That "is simply not on the agenda at this point," despite the United States' continued criticism of Iran's human rights record and suspected nuclear weapons ambitions, she said.
Deputy Secretary of State Richard Armitage has expressly said that regime change in Iran is not the U.S. goal. But Rice would not say whether the United States supports a change of government.
In an earlier conversation with reporters on her plane as she began her weeklong trip, Rice said Iran's approach to human rights and its treatment of its own citizens were loathsome.
"I don't think anybody thinks that the unelected mullahs who run that regime are a good thing for the Iranian people and for the region," she said Thursday. On Friday, she referred to Iran's leaders as "an unelected few."
In London, first stop on a tour of European capitals, Rice said there is broad international agreement that Iran cannot be allowed to use a civilian nuclear power project to conceal a weapons program.
After a meeting with British Foreign Secretary Jack Straw, Rice was asked directly whether the United States might attack Iran. Doing so could presumably head off the threat that Iran could use a nuclear device against Israel or other nations.
"The question is simply not on the agenda at this point," Rice said at a news conference.
Rice said, "We believe particularly in regard to the nuclear issue that while no one ever asks the American president to take all his options, any of his options off the table, that there are plenty of diplomatic means at our disposal to get the Iranians to finally live up to their international obligations."
She called the Iranian human-rights record "abysmal." Earlier, Rice said the Iranian regime's behavior in that area and others "is something to be loathed."
Asked during the plane trip here whether the United States should get more directly involved in the talks the Europeans are having with Iran, she said, "The Iranians know what they need to do. It's not the absence of anybody's involvement that is keeping the Iranians from knowing what they need to do."
Ambassador John Bruton, the European Union's senior diplomat in Washington, told CBS News Reporter Charles Wolfsonas Rice began her trip that it is "important for Iran to see all relevant parties to be engaged." Terming the Bush administration's stance to date as "distant," Bruton says negotiators will have a hard time getting Tehran's bottom line "if Iran thinks the U.S. is not engaged."
Earlier, Rice met with British Prime Minister Tony Blair, the United States' closest ally in Iraq, holding her first meeting with a foreign leader since taking over from Colin Powell as the top American diplomat.
Their 90-minute breakfast meeting at Blair's Downing Street office covered Iraq, the Middle East and other subjects.
Rice thanked Blair for Britain's support in Iraq "as we work to support the Iraqi people in their quest and most especially ... as we try to bring to the Israelis and the Palestinians a chance for a lasting peace."
London is the site of a one-day conference in March to help the Palestinian government build democratic institutions.
En route to London on Thursday, Rice indicated the United States may take a back seat for now in the international effort to bring Israel and the Palestinians closer to a lasting peace.
Rice said she does not plan to attend next week's Middle East summit meeting in Egypt, although she will be close by for talks in Jerusalem and the West Bank.
"Not every effort has to be an American effort," Rice said. "It is extremely important that the parties themselves are taking responsibility. It is extremely important that the regional actors are taking responsibility."
She said the United States welcomes Egypt's help in hosting the summit and called it one of several hopeful signs for peace.
Middle East peace is one of the main topics for Rice's discussions with European leaders over the coming week, as is Iran. She will visit eight European capitals and the Vatican, with a weekend side trip to see the Israeli and Palestinian leaders.