Hollande, appearing at a White House news conference with President Barack Obama, said the two leaders agreed on the importance of closing the Turkish border to limit the movement of extremists into Europe.
Obama emphasized the long friendship between France and the United States and pledged to step up efforts to combat terrorism alongside its European partners.
"As Americans, we stand by our friends in good times and in bad, no matter what," Obama said.
Hollande is trying to rally support this week for a more coordinated international campaign to destroy Islamic State. He is due to visit Moscow on Thursday.
"We are here today to declare that the United States and France stand united in total solidarity to deliver justice to these terrorists and those who sent them and to defend our nations," Obama said.
Obama called Islamic State a "barbaric terrorist group," adding that "its murderous ideology poses a serious threat to all of us. It cannot be tolerated. It must be destroyed. And we must do it together."
Hollande said the United States and France agreed to step up strikes in Syria and Iraq against Islamic State. But Hollande said France will not put troops on the ground in Syria to fight Islamic State.
"France will not intervene militarily on the ground," Hollande said.
Hollande's meeting with Obama follows the attacks in Paris that killed 130 people at the national sports stadium, a concert venue and bars and restaurants in heart of the French capital. Islamic State has claimed responsibility for the attack.
Obama said he and Hollande agreed that more needed to be done to combat Islamic State's efforts.
"US assistance has supported recent French strikes in Syria and we're going to keep stepping up that coordination," he said. "We will continue to do everything in our power to defend our nation."
"We will win and groups like ISIL will lose," Obama said, using an acronym for Islamic State.
"It's been noted that the terrorists did not direct their attacks against the French government or military. Rather, they focused their violence on the very spirit of France and, by extension, on all liberal democracies," Obama said.
"Vive la France," Obama added.
On the Syrian crisis, Obama also said that Russian strikes against moderate opposition there only serve to bolster Syrian President Bashar al-Assad's government.
Hollande would not provide a date for Assad's transition from power but said it must be "as soon as possible."
