Al-Qaeda has insisted it has no links with the Islamic State in Iraq and the Levant (ISIS), which has been locked in deadly clashes with rebels in Syria.
An online statement purportedly from the group's general command said ISIS was "not a branch of al-Qaeda".
Last May, Ayman al-Zawahiri rejected an attempt by the Iraq-based group to merge with the al-Nusra Front in Syria.
Since then, ISIS has been condemned for attacking fellow rebels and abusing civilian supporters of the opposition.
As many as 2,300 people are reported to have been killed in the confrontations between ISIS's predominantly foreign fighters and rebels from both Western-backed and Islamist groups.
On Sunday, at least 16 Islamist rebels were killed when an ISIS suicide bomber blew himself up at their headquarters in Aleppo province.
Another 26 people, including senior military commanders of the Tawhid Brigade, reportedly died on Saturday in Aleppo in twin suicide bombings blamed on ISIS, while a prominent commander of the Suqour al-Sham group was killed in an ambush in Hama, to the south.
ISIS fighters have also taken over the Iraqi city of Fallujah in the past month, and face what appears to be an imminent assault by the army.
'Damaging to the revolution'
ISIS grew out of the former Islamic State of Iraq (ISI), a jihadist militant umbrella group that is believed to have helped create the al-Nusra Front in mid-2011.
In April 2013, ISI leader Abu Bakr al-Baghdadi announced the merger of his group and al-Nusra - effectively a takeover - and the creation of the Islamic State in Iraq and the Levant (ISIS).
But the move was rejected by al-Nusra leader Abu Mohammed al-Julani and Zawahiri, al-Qaeda's overall leader, who recognised al-Nusra as its sole Syrian offshoot.
Since then, ISIS and al-Nusra have operated as separate entities, with the latter focusing on toppling President Bashar al-Assad and maintaining better relations with other rebels. ISIS has seemed to be more concerned by territorial gains and implementing its extreme interpretation of Islamic law.
On Sunday, a statement by al-Qaeda General Command was published on jihadist web forums that sought to distance itself from ISIS.
"[Al-Qaeda] has no connection with the group called the ISIS, as it was not informed or consulted about its establishment. It was not pleased with it and thus ordered its suspension. Therefore, it is not affiliated with al-Qaeda and has no organisational relationship with it.
"Al-Qaeda is not responsible for ISIS's actions," it added.
The General Command also emphasised that the group's leaders "disavow sedition among the mujahideen factions in the Levant" and the "shedding of protected blood".
Charles Lister, a visiting fellow at the Brookings Doha Center, said the statement was an attempt by al-Qaeda to definitively reassert some level of authority over the jihad in Syria.
But he added that ISIS was unlikely to heed the appeal to end the infighting.
"Considering its long-established behavioural norms, it seems unlikely that ISIS will issue anything representing an apology or retraction," he told the AFP news agency.
"All of this is damaging to the Syrian revolution," he added. "So long as it continues, these inter-group hostilities make any kind of provincial, let alone national, opposition victory in Syria highly unlikely."