It was not immediately possible to authenticate the statement.
US Democrats, who removed Republicans from power in Congress in November last year amid growing dissatisfaction with policies on Iraq, were also criticised by al-Zawahiri.
"The people chose you [Democrats] due to your opposition to Bush's policy in Iraq, but it appears that you are marching with him to the same abyss"
Ayman al-Zawahiri, al-Qaeda deputy
He said: "The people chose you [Democrats] due to your opposition to Bush's policy in Iraq, but it appears that you are marching with him to the same abyss, and it appears that you will take part with him in the defeat."
He also said US-allied governments in Iraq and Afghanistan should consider their future.
"These traitors in Iraq and Afghanistan must face their inevitable fate, and face up to the inescapable facts. America ... is about to depart and abandon them, just as it abandoned their like in Vietnam."
Al-Zawahiri repeated his previous condemnation of the Fatah faction led by Mahmoud Abbas, the Palestinian president.
He said: "I'm not asking them to join Hamas, the Islamic Jihad or al-Qaeda, but rather I'm asking them to return to Islam, in order to fight for the establishment of an Islamic state over all of Palestine and not for the establishment of a secularist state which will please America."
Addressing Lebanon's Muslims, al-Zawahiri urged them to reject the UN Security Council resolution that ended last summer's war between Hezbollah and Israel.
"I call on the brothers of Islam and of jihad [struggle] in Lebanon not to yield to resolution 1701 and not to accept ... the presence of international and Crusader [Western] forces in south Lebanon.
Security Council resolution 1701 led to an August 14 ceasefire in the 34-day war that broke out when Israel retaliated to a cross-border raid by Lebanese Hezbollah fighters which resulted in the capture of two of its soldiers.