President Bush said he was taking the action because Hamas claimed responsibility for Tuesday's suicide attack on a packed bus in Jerusalem that killed 20 people, including six children.
The move, being carried out by the Treasury Department, also targets six top Hamas leaders.
It's a new effort by the White House to destroy Hamas, reports CBS News Correspondent Mark Knoller.
A senior administration official, speaking on condition of anonymity, said it was the first effort to block Hamas' assets or funding sources outside the United States. Similar action has been taken worldwide against al Qaeda and other terrorist networks, however.
The Jerusalem bombing prompted a new round of Mideast violence, and a threat from Israel to kill more militant chiefs in raids mirroring a lethal missile strike on a top Hamas leader Thursday.
On Friday, a Palestinian militant wanted by Israel was shot and killed on the roof of a hospital in Nablus, on the West Bank. Two other militants were wounded.
The Israeli military says the man killed was involved in the suicide bombing ten days ago that left an Israeli man dead at a supermarket in central Israel.
In the funeral procession in Gaza City Friday for Ismail Abu Shanab, men carried the bodies of Abu Shanab and his two bodyguards. The streets echoed with shouts for revenge. Some in the crowd chanted together a warning for Israeli Prime Minister Ariel Sharon and Defense Minister Shaul Mofaz: "Sharon and Mofaz listen very well, our retaliation will send you to hell."
However, Israel has decided to give the Palestinian Authority 24 hours to confront the terror organizations, Haaretz newspaper reported.
Osama El-Baz, the political advisor to Egyptian President Hosni Mubarak, who met with Palestinian Authority chairman Yasser Arafat in Ramallah and Israeli Foreign Minister Silvan Shalom later in the day, called on Israel to allow more time.
Palestinian leaders said Thursday's killing of Shanab, a top aide to Hamas chief Ahmed Yassin, ruined what was to be an imminent campaign against militants by Palestinian security forces that would have included arrests and weapons roundups.
The militants called off their two-month-old cease-fire and promised more suicide bombings and other attacks on Israeli targets, raising the chances that a new round of Mideast violence will sink a U.S.-backed peace plan that aims to stop three years of violence and create a Palestinian state.
Hamas quickly dispatched squads of young activists in Gaza to launch homemade rockets into Israel. By Friday morning, six of the crude projectiles had been fired, damaging two houses but causing no injuries. More than a dozen mortars were also launched at Jewish settlements within Gaza, damaging another house.
Several high-ranking Israeli military officials said on condition of anonymity that there were plans to kill other top Hamas leaders if there are new Palestinian suicide attacks and no efforts by Palestinian police forces to arrest extremists.
Speaking at the funeral of Abu Shanab, another Hamas leader, Abdel Aziz Rantisi, who survived an Israeli rocket attack on his car in June, said that if the Israelis kill him and other top militants, a secret leadership is ready to take over.
"They think that targeting leaders will stop Jihad (holy war). They are mistaken," he said. "All of us in Hamas from top to bottom are looking to become like Abu Shanab."
A Palestinian suicide bombing on a Jerusalem bus on Tuesday killed 20 people, including six children, prompting Israel's strike on Abu Shanab, a 53-year-old Hamas leader and U.S.-educated civil engineer.
An Israeli security source said all Hamas leaders were now considered fair targets and new strikes would be launched after a 24-hour lull to give Palestinians a chance to act on their own against militants. "We were waiting to see even just one Hamas arrest," he said.
"Hamas has reaffirmed that it is a terrorist organization committed to violence against Israelis and to undermining progress toward peace between Israel and the Palestinian people," said President Bush, who stopped in Burbank, Wash., for an event about his salmon restoration policies during a two-day trip through the Pacific Northwest.
Mr. Bush called on "all nations supportive of peace in the Middle East" to recognize Hamas as a terrorist organization and to join the United States in freezing the groups' funds.
The senior administration official said several European countries appear supportive of the asset freeze, but that the administration was waiting to see the official response.