"We stress the necessity of sparing the Palestinian people any internal confrontations and to avoid using weapons as a medium for dialogue and to focus on dialogue only to solve our differences," he said before a Cabinet meeting. "The differences exist, they are there, but this does not mean that they should be solved by gun fire."
Haniyeh's Islamic Hamas group, which controls the Cabinet and parliament, and the more moderate Fatah, headed by President Mahmoud Abbas, have been engaged in bloody street battles that have killed 35 Palestinians over the past month.
On Tuesday, another Hamas militant died from wounds sustained in fighting last week and new skirmishes erupted between the rival Palestinian groups in Gaza. At night, a car refused to stop at a Fatah roadblock near Abbas' office and gunmen inside opened fire, seriously wounding two guards.
Haniyeh said the fighting "will please enemies of the Palestinians, who want to see civil war."
Haniyeh spoke a day after Hamas-linked militants gave their first word on the condition of an Israeli soldier they captured more than six months ago.
"Gilad Shalit is in good health and is being treated according to Islamic standards of dealing with prisoners of war," said Abu Mujahid of the Palestinian Resistance Committees, a militant group linked to Hamas. "We are ready to keep him for years, as long as our demands are not met."
The impasse over the soldier has held up peace efforts in other areas between Israel and the Palestinians.
Abu Mujahid did not elaborate on the "Islamic standards" of treating a prisoner.