Friday's announcement is a setback to plans of Mahmoud Abbas, the Palestinian president, to form such a unity government.
Ahmad Yusuf, political adviser to Ismail Haniya, the prime minister, told Reuters that an agreement between Hamas and Abbas to form a coalition did not include recognition of Israel.
"I rule that out. The political thinking of Hamas prevents the idea that Hamas can be part of a government which puts the recognition of Israel on its political agenda," Yusuf said.
A deal on a unity government was reached on September 11, and Palestinians hope it will lead to a lifting of sanctions imposed on Hamas when it was elected into office in March.
Talks on the coalition's formation have faltered since and Abbas, whose Fatah movement was defeated by Hamas in January elections, has accused Hamas of reneging on the deal.
"I rule that out. The political thinking of Hamas prevents the idea that Hamas can be part of a government which puts the recognition of Israel on its political agenda"
adviser to Ismail Haniya
Yusuf reiterated Hamas's position that a unity government would honour agreements made with Israel as long as they were in the "interests of the Palestinian people".
Those agreements include the 1993 Oslo peace accords.
Saeb Erekat, the senior Abbas aide, expressed surprise at Yusuf's comments, saying Hamas signed the deal on forming the unity government knowing it meant honouring past peace deals.
Condoleezza Rice, the US secretary of state, meanwhile has said she will visit the Middle East soon.
Speaking after a UN Security Council meeting to discuss the Middle East on Thursday, Rice said she would seek out "moderate" Arab leaders on her trip and try to help both sides in the Arab-Israeli conflict resolve their differences.
"I expect to go to the region fairly soon," said Rice, without giving details.
Rice said she would try to "accelerate progress" on the US-led road map for Middle East peace.
The road map lays out steps for a two-state solution in which Israel and a Palestinian state live side by side.