Noting that American citizens were also killed, Bush told Singh that he would be working with the international community to provide all the necessary help in the investigation of the attacks, White House spokesman Gordon Johndroe said.
The attacks, which killed at least 174 people, including 18 foreigners, in India's financial capital, ended Saturday when commandos killed the last three gunmen inside a luxury hotel.
Bush told Singh that he has directed the State and Defense Departments along with other federal agencies to devote the necessary resources and personnel to the situation, Johndroe said.
Bush told Singh he believes this tragedy can create an opportunity "to hold these extremists accountable and demonstrate the world's shared commitment to combat terrorism," Johndroe said.
FBI agents arrived in India on Sunday. A second group of investigators was on alert to join the first team if necessary. The State Department warned U.S. citizens still in the city that their lives remain at risk.
On Saturday, Bush pledged full U.S. support to India in a brief statement at the White House after returning from the Camp David presidential retreat where he spent Thanksgiving and monitored the rampage. Bush said the killers "will not have the final word."