"I look forward to deepening counter-terror cooperation when I meet Prime Minister (Manmohan) Singh," Obama said to families of some of the victims of the November 2008 carnage that saw terrorists slaughter 166 people, six Americans included.
"The US and India are working more closely together than ever to keep our nations safe," Obama said in his first remarks after he touched down in Mumbai with wife Michelle to begin a four-day visit to India.
The 49-year-old president was speaking at the Taj Mahal Palace and Tower Hotel, one of the targets of the Pakistani terrorists.
"The torch of freedom should not be blown off. History is on our side. The murderers who targeted the innocent people have nothing to offer but death and destruction," he said.
Expanding counter-terror cooperation will figure prominently in talks between Manmohan Singh and Obama in New Delhi Monday.
The president said he would "never forget the awful images of 26/11".
Obama, however, did not name Pakistan or terrorist networks in the region in his brief speech at the "historic" Taj hotel. India blames Pakistan for the Mumbai strike that almost sparked an India-Pakistan war.
"Taj has been a symbol of strength and resolve. Mumbai has been a symbol of incredible energy and optimism," Obama said.
The terrorists targeted places where Hindus, Muslims, Sikhs, Christians and Jews protected each other, Obama said while lauding Mumbai's religious and cultural diversity.
"Here in Mumbai, the diversity that is India's strength was in full display... Those who attacked Mumbai wanted to demoralize this city and this country but they failed. The very next day, Mumbaikars came back to work... Within weeks, this hotel was welcoming guests from around the world."
The US president is on his maiden visit to India, focused largely on the American hunt for markets and jobs.
With an hour of landing at the Chhatrapati Shivaji International Airport, Obama took off in a US helicopter and then his Cadillac to reach the Taj hotel at the edge of the Arabian Sea.