By Daniel Burke and Mitra Mobasherat, CNN

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(CNN) - Marking a sharp shift from his Holocaust-denying predecessor, new Iranian President Hassan Rouhani on Wednesday appeared to wish "all Jews" a "blessed Rosh Hashanah" on his English-language Twitter account.

As the sun is about to set here in #Tehran I wish all Jews, especially Iranian Jews, a blessed Rosh Hashanah. pic.twitter.com/tmaf84x7UR — Hassan Rouhani (@HassanRouhani) September 4, 2013

Rosh Hashanah, of course, is the Jewish celebration of the new year. As Rouhani mentions, it began Wednesday at sundown. The image in the tweet is reportedly taken from a synagogue in Tehran.

Rouhani, a Shiite Muslim cleric, was elected president in June. He is widely seen as more moderate than former president Mahmoud Ahmadinejad, though his goodwill gesture on Wednesday stunned even veteran Iran watchers.

“Not even under the monarchy do we remember such a message,” Haleh Esfandiari, a native Iranian and director of the Middle East program at the Woodrow Wilson International Center, told Al-Monitor.

On Thursday, however, Mohammadreza Sadegh, an adviser to Rouhani, told Iran's Fars News Agency that the Rosh Hashanah tweet did not come from the Iranian president. The tweet came from former campaign aides, rather, who run the Twitter account, Sadegh said.

"All the news regarding the president, after his election, is reflected by his appointed bureau chief and those are the only official reports. Mr. Rouhani does not have a Twitter account," Sadegh told Fars.

A close aide to Rouhani, however, told CNN’s Christiane Amanpour that while the president does not tweet from his account, people in his office do, so it is semi-official.

Interest in Rouhani's Twitter account was nearly eclipsed on Thursday by extraordinary Tweets from the official account of Javad Zarif, Iran's foreign minister.

Happy Rosh Hashanah — Javad Zarif (@JZarif) September 5, 2013

@sfpelosi Iran never denied it. The man who was perceived to be denying it is now gone. Happy New Year. — Javad Zarif (@JZarif) September 5, 2013

If the name of Zarif's interlocutor looks familiar, it should. @SFPelosi is the Twitter account of House Minority Leader Nancy Pelosi's daughter, Christine Pelosi.

Ahmadinejad isn't as tech savvy nor as pluralistic as Rouhani, but on a few occasions, he would issue positive statements about Christmas or Rosh Hashanah.

The former Iranian president was much more widely known, however, for saying that Israel should be eliminated and calling the Holocaust a myth. Usually, Ahmadinejad would caution that he was criticizing "Zionists," not all Jews.

Fewer than 10,000 Jews remain in Iran, according to the JTA, the Jewish news service, which still makes it the largest Jewish community in the Middle East outside of Israel.

Religious minorities are not completely free to participate in Iranian government and often face discrimination, but Jews and Christians are, to some extent, allowed to live and worship openly in Iran.

As Washington Post foreign policy expert Max Fisher points out, it's difficult to extricate Rouhani's tweet from the context of Israeli-Iranian politics.

"It’s not exactly a unilateral declaration of peace – tomorrow, Iran will probably still support Hezbollah – but it’s yet another hint of Rouhani’s efforts to dramatically soften Iranian foreign policy and rhetoric," Fisher writes.

In honor of Rosh Hashanah, here are some other things to know about the Jewish holiday:

According to the Talmud, the world was created on the first day of Tishri, the seventh month of the Jewish calendar. So Rosh Hashanah is considered a birthday of sorts for the world. (Other rabbis teach that it honors the day Adam and Eve were created.)

It is celebrated on the first and second days of the month of Tishri, which generally corresponds to September or October on the Gregorian calendar.

Rosh Hashanah begins the High Holy Days or Ten Days of Penitence, which end 10 days later with Yom Kippur.

One of the most significant rituals during Rosh Hashanah is the blowing of the Shofar, or ram's horn. It is used as a call to repentance during the High Holy Days.

During this time, Jewish people attend synagogue services and refrain from working.

Another popular practice is to eat apples dipped in honey, symbolizing the hope for a good year to come. Also, challah bread in round loaves instead of braided loaves is dipped in honey instead of salt.

Pomegranates are eaten because the seeds are symbolic of the many commandments in the Torah that Jews must fulfill.

Another popular ritual is to walk to a river or stream and recite special prayers of penitence. Afterwards, one throws breadcrumbs in the river, to symbolically cast away sins.