Haniya urged an end to internal violence on Saturday and called for fresh efforts to form a unity Palestinian government.
At least 30 Palestinians have been killed in factional fighting since Mahmoud Abbas, the Palestinian president and leader of the rival Fatah, called last month for early parliamentary elections to try to break a political deadlock with Hamas over creating a unity cabinet.
The Hamas government, formed in March, has also been hit hard by an international aid boycott and had only paid partial salaries to 165,000 employees.
Haniya said: "I call on the Palestinian people and factions, in particular Hamas and Fatah, to halt internal clashes.
"We must protect national unity and work to form a national unity government."
Hamas took control of the government in March, after beating the once dominant Fatah in elections.
On Saturday, officials from both sides said significant progress has been made in secret coalition talks between the supreme Hamas leader and envoys of Abbas.
Moussa Abu Marzouk, deputy head of Hamas's political bureau in Damascus, confirmed the secret talks and said Khaled Meshaal, the exiled Hamas leader, would meet Abbas early next week in the Syrian capital.
"I hope his meetings in Damascus would be constructive and lead to a resolution of all outstanding problems that have ruptured the dialogue in the past," he said.
An Abbas aide said the meeting would take place on Monday.
Al Jazeera's correspondent in Damascus reported quoting two aides of Abbas that agreement has been reached on identifying independent figures to run the finance and foreign ministries, with Haniya holding on to the prime minister's post.
Ziyad Abu Amr and Mohammed Rashid, the aides, were headed first for Doha to meet Qatari officials, and then for the Syrian capital again to arrange for the Abbas-Meshaal meeting.
For his part, the Palestinian left for Jordan on Saturday to brief Jordan's King Abdullah II on the developments.
On Sunday, he is to be back in the West Bank, to meet Condoleezza Rice, the US secretary of state, who is touring the Middle East.
In another development, the Palestinian civil servants' union announced on Saturday that it was ending a 135-day strike it had launched to protest against non-payment of salaries by the government.
The union is dominated by Fatah and the strike was seen as part of the power struggle between the two sides.
All civil servants will go back to work on Sunday, Bassam Zakarneh, the head of the union, said at a joint news conference with Samer Abu Aisheh, finance minister, and Nasser Shaer, deputy prime minister, both of Hamas.
In September, about half the civil servants, including teachers and health care workers, went on strike, while 80,000 members of the security forces remained on the job.
The finance minister said full salaries will be paid, starting next month, and that the back wages will be paid in instalments.
Abu Aisheh said the government has more than $30m in donations in an Arab League account and that Qatar has promised $22m.