The caricatures, which included depictions of the Muslim prophet as a knife-wielding bedouin and another as wearing a time bomb-shaped turban, have sparked widespread protests in the Muslim world.
Hashem al-Khalidi, editor-in-chief of a weekly tabloid called Al-Mehwar which printed the cartoons in its 26 January edition, was arrested shortly before midnight on Saturday (2200 GMT), the source close to Khalidi told AFP.
Jihad Momani, the former editor-in-chief who was sacked on Friday from the helm of the weekly gossip newspaper Shihane, was earlier arrested on the order of prosecutors for having printed three of the cartoons, a judicial source told AFP.
Shihane published the drawings on Thursday, and the paper's publisher subsequently pulled all editions from the newsstands.
The cartoons had appeared along an editorial by Momani appealing to Muslims to "be reasonable."
Momani later expressed his "deep regret and guilt for the serious mistake committed involuntarily by Shihane," according to a letter published by the official Petra news agency.
As Momani's arrest was announced, authorities also pledged to "open an investigation" into Al-Mehwar, the judicial source said.
"The fact alone that this weekly (Al-Mehwar) reproduced these cartoons renders its editor-in-chief Hashem al-Khalidi responsible before the law," the source said, adding that "al-Khalidi's arrest is only a matter of time."
Al-Mehwar reprinted them to accompany an article on widespread condemnation of the sketches.
"The fact alone that this weekly (Al-Mehwar) reproduced these cartoons renders its editor-in-chief Hashem al-Khalidi responsible before the law"
Unnamed source close to al-Khalidi
It claimed to be the "first Arab newspaper to have alerted the Arab world to these cartoons, discovered on the Internet".
The 12 cartoons were first published in September 2005 by the Danish newspaper Jyllands-Posten and have since reappeared in a number of European publications.
Jordan's King Abdullah II on Friday said that insulting the Prophet Mohammed was "a crime that cannot be justified under the pretext of freedom of expression".
His words were seen by security forces as a signal to take action against the newspapers.
Islamic custom forbids the production of any image of the Prophet and considers any such depiction as a form of blasphemy.
The publication of the cartoons has caused uproar among Muslims who deem them offensive to Islam.