Donald Trump's Middle East envoy has said Hamas must renounce violence and commit to negotiations with Israel if it wants to play a role in any Palestinian government.
They are demands the Islamic militant group has always rejected.
Jason Greenblatt's statement was the first American comment on advancing reconciliation efforts between the rival Palestinian Fatah and Hamas factions, and echoed Israeli demands.
"Any Palestinian government must unambiguously and explicitly commit to non-violence, recognise the state of Israel, accept previous agreements and obligations between the parties - including to disarm terrorists - and commit to peaceful negotiations," Mr Greenblatt said in a statement.
"If Hamas is to play any role in a Palestinian government, it must accept these basic requirements."
Hamas seized control of the Gaza Strip from President Mahmoud Abbas's Fatah-led forces in 2007, leaving Mr Abbas only in control of autonomous areas of the Israeli-occupied West Bank.
Past attempts at reconciliation have failed, but after a decade-long blockade by Israel and Egypt, and three wars with Israel, Hamas has said it is ready to compromise.
Under Egyptian auspices, the Palestinian factions last week reached a preliminary agreement and have formed committees to sort out unresolved issues, most notably who will control Hamas's massive arsenal. The deal has yet to be implemented.
A White House official said Mr Greenblatt was travelling to Egypt to talk to officials about the Palestinian reconciliation efforts.
Mr Greenblatt has been shuttling through the region in search of a formula to restart Israeli-Palestinian peace talks, which last broke down in 2014. His statement on Thursday reiterated long-standing demands of Hamas by the international community.
Israeli prime minister Benjamin Netanyahu said this week there would be no talks with the Palestinians unless Hamas agrees to the same conditions.
Mr Netanyahu, who welcomed Mr Greenblatt's statement, has added some additional demands, including that Hamas disarm and return the remains of two Israeli soldiers and send back two Israeli civilians believed to be in Hamas captivity.
Hamas, which is considered a terrorist group by Israel, the US and other Western nations, does not plan to officially be part of the next government.
The Palestinians appear to be hopeful that this will be enough to satisfy the international community, but Hamas has said it will not dismantle its powerful military wing, and it is likely to wield influence behind the scenes.
In a statement, Hamas said it rejected "the extortion and American bias toward the Israeli positions expressed by Jason Greenblatt".
"Hamas will go ahead in the reconciliation and will not pay attention to any attempt to sabotage or block this track," it said.
Mr Abbas seeks an independent state in the West Bank, east Jerusalem and Gaza. Israel captured the territories in 1967, though it withdrew from Gaza in 2005.
With peace efforts on hold, Israel this week pushed plans ahead for 3,000 new homes in West Bank settlements, according to Peace Now, an Israeli anti-settlement monitoring group.
The planned units are scattered throughout the West Bank and at various stages of approval. Peace Now estimated that roughly 700 of them can be built immediately.