The 14-minute audio message -- which purportedly is al-Zawahiri's second this week -- was posted to jihadist forums on Friday. CNN could not independently verify its authenticity.

The language used in the last posting resembles that in other messages attributed to al-Zawahiri in which he criticizes the treatment from various parties of Morsy, the former Muslim Brotherhood leader who last year became Egypt's first democratically elected president.

"The crusaders, the seculars, the Americanized army, (former President Hosni) Mubarak's thugs and some members of Islamic parties with the support of Gulf money and American plotting, all agreed to topple Mohamed Morsy's government," he says.

Those behind Morsy's ouster, the message states, wanted a "secular, pro-American president to rule Egypt so they can continue with their plotting -- along with the Americans and Zionists -- to divide Egypt, just like what happened in Sudan."

The 62-year-old Al-Zawahiri is no stranger to Egypt or its politics.

A member of a distinguished Egyptian family, he is a surgeon who with the Egyptian Islamic Jihad tried to overthrow President Anwar Sadat and establish an Islamic state. After Sadat's assassination, al-Zawahiri was arrested and convicted on weapons charges.

He met Osama bin Laden in the late 1980s and, in about a decade later, merged the Egyptian Islamic Jihad with al Qaeda.

The message posted Friday comes three days days after another message purportedly from al-Zawahiri appeared online, although it was believed to be recorded June 5.

In that message, the voice purportedly of al-Zawahiri denounced U.S. treatment of hunger-striking detainees at its Guantanamo Bay military prison and pledged to free them. He also urged Muslims -- as he and other al Qaeda leaders have many times before -- to unite and fight.

"Every Muslim in every spot on Earth must work to defend the blood of Muslims that is being shed by America and its allies, and their sanctities that they are violating, and their villages and homes that they are destroying, and their wealth that they are stealing," he said.