A much-anticipated greeting between President Obama and Iranian President Hassan Rouhani did not take place here because American officials seemed to have no firm strategy for what would come next, the new Iranian leader said Wednesday.

“We need a plan” to establish better relations after more than 30 years of estrangement, Rouhani said. “In principle, we were not opposed to meeting at all.”

Obama and Rouhani both spoke Tuesday at the opening of the United Nations General Assembly and could have arranged an informal encounter at a luncheon for leaders hosted by U.N. Secretary General Ban Ki-moon. The Americans reached out to propose such a brief meeting, Rouhani told media executives Wednesday.

But the timing was not right, and there was too much at stake to squander the chance, Rouhani said.

“If we do not take our first steps carefully, we may not at the very least be able to obtain mutual goals that are in our minds,” Rouhani said through an interpreter.

In the same session, Rouhani called the Holocaust “a massacre of the Jews by the Nazis,” in contrast to past Iranian statements that cast doubt on the historical event that led to the establishment of Israel as a Jewish state. Iran officially considers Israel illegitimate.

Although Rouhani said Iran completely condemns the Holocaust, he said it is important that victims “not seek compensation by victimizing other groups.”

That was a reference to Palestinians displaced by Israel’s founding and to Israel’s occupation of West Bank land that the Palestinians seek for an independent state.

Rouhani would not address what he called the “scale and numbers” of the Holocaust. “Why don’t we just leave that to the experts?” he said.

The American explanation for why an Obama-Rouhani breakthrough did not come about this week was that it became clear that domestic politics in Iran prevented Rouhani from making a bold move. U.S. officials said Tuesday that despite some promising early exchanges with Iran’s U.N. mission, it was “too complicated” for Rouhani to proceed.

A handshake, simple as it might seem, would have been the first direct contact between a U.S. president and an Iranian leader since the Carter administration. It would have signaled the first real progress on Obama’s campaign offer to “extend a hand if you are willing to unclench your fist.”

Rouhani is working to present a more reasonable face to the world than his predecessor as president, Mahmoud Ahmadinejad. Rouhani, a relative moderate, won a surprise election victory in June. He appears to have the backing of Iran’s supreme leader, Ayatollah Ali Khamenei, in his effort to improve Iranian relations with the United States and resume more meaningful negotiations over Iran’s disputed nuclear program.

Former State Dept. spokesman P.J. Crowley explains what President Obama's remarks at the U.N. General Assembly mean for broader U.S. policies in the Middle East and what role the U.N. should play there. (The Washington Post)

Letters exchanged between Obama and Rouhani encouraged observers in both countries that progress was possible. U.S. officials did nothing to discourage speculation about a meeting at the United Nations.

“I believe we did not have enough time to make it happen,” Rouhani said Wednesday.

Iran’s Foreign Ministry had appeared to rule out a meeting early in the day Tuesday, before either leader addressed the world body.

Obama’s speech, in which he talked about Iran’s right to maintain a peaceful nuclear program and ruled out regime change, was received favorably by Iranians who viewed his tone as respectful to them. Rouhani’s tone differed significantly from the ranting Ahmadinejad, but he made no real new overtures.

In Wednesday’s group interview, Rouhani repeated his willingness to negotiate over his country’s nuclear energy program, but he stressed that Iran wants to retain the full ability to enrich uranium on its own soil. It is that ability that most worries the United States and ally Israel, because highly enriched uranium can also be used as fissile material for nuclear weapons.

“There was nothing we wish to hide or should hide,” Rouhani said. “We seek nothing more than our legal rights.”

He made clear that the nuclear program, a centerpiece of Iranian foreign policy for a decade, is a matter of national pride that is not easily traded away.

Other nations are free to enrich uranium for their own domestic nuclear energy needs, and “we want to be viewed as one of those,” Rouhani said. “Nothing less, nothing more.”

Iran’s economy is staggering under international sanctions and a partial oil embargo that are intended to force the country to provide more information and assurances about its program.

Rouhani’s mandate to approach international nuclear negotiations, which have made no progress in several rounds, appears to be based on Iranian hopes that he can win some fast relief from sanctions.

On Wednesday, Iran’s currency, the rial, was trading at 6 percent lower than the rate it closed at Tuesday, signaling that currency speculators, at least, do not believe there will be sanctions relief soon.

Iranian hard-line political conservatives — those expected to pose the greatest obstacle to rapprochement — have been mostly silent on Rouhani’s speech thus far. That may mean it did not carry any messages they found ideologically unacceptable, and the response from the few hard-liners who made comments was positive.

Sadegh Larijani, the conservative head of Iran’s judiciary and brother of its speaker of parliament, called Rouhani’s speech “firm and logical.”

“Iran has given Obama and the U.S. officials another chance to earn the trust of the Iranian people,” Larijani said.

State media showed coverage from U.S. news programs discussing the response to Rouhani’s speech, as well as clips from a television interview, dubbed into Farsi. American news media also carried portions of Rouhani’s U.N. address live.

Although there was no meeting between Obama and Rouhani, Secretary of State John F. Kerry and Iran’s foreign minister will both attend a round of the international nuclear talks in New York on Thursday. The meeting would be the first direct interaction between the top diplomats from the two countries in more than six years.

Jason Rezaian in Tehran contributed to this report.