Mahmoud Abbas said after Hamas' upset victory in parliamentary elections last month money from donor nations has slowed, the BBC reports.
Hamas is considered a terrorist group by the United States, European Union and Israel for its violent tactics and outright call for destruction of Israel.
The trio have called on Hamas to change its goals in order to keep funding coming to the Palestinian Authority.
The United States has asked for $50 million in funding to be returned.
Acting Israeli Prime Minister Ehud Olmert said its government won't be diplomatic with Hamas.
The Israeli government also approved a series of measures aimed to punish the government but, Olmert said, not intended to hurt ordinary Palestinians.
Israel will withhold tax and custom payments collected on behalf of the P.A., totaling $60 million a month, increase border security and restrict Hamas leaders' movement, ban equipment from getting to security forces there and ask other nations to stop giving money to the Hamas government.
Abbas is to meet Monday with the new Hamas leadership, including Prime Minister Ismail Haniyeh, to form a coalition government.
Abbas is a leader of the Fatah Party, which lost its majority in the January election.