In an audio message, the terrorist organization's second-in-command, Ayman al-Zawahri, said that Obama was "the direct opposite of honorable black Americans" and warned him about sending more troops to Afghanistan.
"What you have announced before ... that you will withdraw [U.S.] troops from Iraq [and send them] to Afghanistan is a policy that is doomed to failure," al-Zawahri said in the message, according to Al-Jazeera.
On the campaign trail, Obama said he would shift the military focus from Iraq to the war in Afghanistan.
Al-Zawahri said Obama would fail if he continued President George W. Bush's policies and did not withdraw from Muslim lands. The message, coming from the militant group that was responsible for the Sept. 11 terrorist attacks, also urged continuing attacks on America, which it called a "criminal, trespassing crusader."
In reaction, the Homeland Security Department said the message did not indicate an increased threat to the U.S.
"We maintain that there's no credible information to suggest there's an imminent threat against the homeland at this time," department spokeswoman Laura Keehner said Wednesday.
Obama's transition team said it would not comment on the message.
Al-Zawahri called Obama a "house negro," a term used by black civil rights leader Malcolm X to describe slaves who were close to their masters, in contrast to "field negros" who worked on the plantation.
The term implies that Obama would do the bidding of white Americans and accuses him of betraying his father's Muslim heritage.
"The Muslim nation received with extreme bitterness your hypocritical ... stance towards Israel," al-Zawahri said. "You were born to a Muslim father, but you chose to stand with the enemies of Muslims."
Obama's Kenyan father was a Muslim, though Obama has insisted that he is a Christian.
According to Islamic law, a person born to a Muslim father who renounces Islam is a Muslim apostate, a fact that Shireen K. Burki, an adjunct professor at the University of Mary Washington in Virginia, said al-Qaida will use against Obama.
"Should Obama become U.S. commander in chief, there is a strong likelihood that Al Qaeda's media arm, As-Sahab, will exploit his background to argue that an apostate is leading the global war on terror (read: attacks against fellow Muslims). This perception would be leveraged to galvanize sympathizers into action," Burki wrote in the Christian Science Monitor before Obama was elected.
"Once branded as an apostate, President Obama would face enormous difficulties in the foreign policy realm, especially in the fight against terrorism," she continued.
Al-Zawahri's message was released on militant Web sites accompanied by pictures of himself, Malcolm X and Obama with Jewish leaders, the Associated Press reported.
It was an attempt to shift the focus from President Bush to Obama and justify future attacks, but is not a new approach to threatening America, said Adam Raisman, an analyst at SITE Intelligence group, according to Reuters.
"It's the same message that he's been carrying for quite a few years -- 'you either leave our lands or suffer the repercussions," Raisman said.