The recording by Ayman al-Zawahri came on the heels of a message from Osama bin Laden calling a holy war to liberate Palestinian lands - a new push by the terror network's leadership to use widespread anger over the Gaza violence to whip up support.
The authenticity of the 4 minute, 44-second audiotape could not be independently confirmed. But the voice on it resembled that of al-Zawahri on previous audio and videotapes confirmed to be his.
It was posted on an Islamic militant Web site where Al-Qaida usually releases its statements, and a banner advertising the tape had the logo of Al-Qaida's media arm, Al-Sahab.
"Muslims, today is your day. Strike the interests of the Jews, the Americans, and all those who participated in the attack on Muslims," the Al-Qaida leader said.
Al-Zawahri continued: "Monitor the targets, collect money, prepare the equipment, plan with precision, and then - while relying on God - assault, seeking martyrdom and paradise."
Israel launched the IDF operation in early March to combat Gaza militants' rocket attacks on communities bordering the coastal strip. Two IDF soldiers were killed and eight were wounded, one moderately. The Palestinians reported 70 dead, and another 50 killed in other incidents since the operation began.
Al-Zawahri said attacks should not be limited to places in Israel and the Palestinian territories.
"Today there is no room for he who says that we should only fight the Jews in Palestine," he said. "Let us strike their interests everywhere, just like they gathered against us from everywhere."
"Let them know that they will get blood for every dollar they spend in the killing of the Muslims, and for every bullet they fire at us, a volcano will turn back on them," he said. "They cannot expect to support Israel, then live in peace while the Jews are killing our fugitive and besieged people."
AL-Zawahri also referred to the publishing of a cartoon seen as insulting Islam's Prophet Muhammad in Danish papers. The cartoons, which were first printed in 2006 and reprinted this month, angered many Muslims.
"They will never be able to insult and make a mockery out of our Prophet, peace and prayers of Allah upon him," al-Zawahri said.
Al-Zawahri also accused Egyptian President Hosni Mubarak of colluding with Israel in the siege of Gaza. Egypt has sealed its border with the Gaza Strip since the Palestinian militant group Hamas took over the territory last year.
He said Mubarak repeats "the same dirty role as the Lebanese Phalangists" - a Christian militia that was allied with Israel in Lebanon's 1975-1990 civil war and was blamed in the massacre of Palestinian refugees in the Beirut camps of Sabra and Shatila. "The roles are the same, even if the faces change - the same betrayal even if the names have changed," said al-Zawahri.
In an audio recording aired by Al-Jazeera last week, Al-Qaida leader Osama bin Laden called on Palestinians to use "iron and fire" to end an Israeli blockade on the Gaza Strip and liberate their country.
The pan-Arab television network described the tape as a new recording.