“We’re going to have to do more to prevent these kinds of events from occurring. It’s going to take more than just our military,” Mr Obama said, an apparent reference to proposals for stricter gun-control laws.
That was after he laid flowers at a makeshift memorial during an visit to the grieving city.
“We can’t wipe away hatred and evil from every heart in the world. But we can stop some tragedies. We can save some lives,” he said.
Mr Obama praised the Senate for scheduling votes next Monday on gun control measures, although the legislation is likely to fail.
Mr Obama travelled to Orlando as the city prepared to bury its first victims from the mass shooting.
The president and vice president Joe Biden spent hours meeting privately with survivors, victims’ relatives, and police officers.
Yesterday, Democratic senator Chris Murphy forced a marathon debate in the senate of nearly 15 hours over gun control.
He deployed the filibuster technique, designed to block proceedings, in a bit to incite a compromise on the stalled gun issue.
He spent much of the time speaking about the shooting at Sandy Hook Elementary School, in his home state, Connecticut, in December 2012.
When he had been standing on the floor for over nine hours, his sons, ages four and seven, briefly appeared in the senate gallery.
“I hope you’ll understand some day why we’re doing this,” he said, addressing his oldest son. “Trying and trying and trying to do the right thing is ultimately just as important as getting the outcome in the end.”
The debate pits strong proponents of the Second Amendment right to bear arms against those arguing for greater restrictions on the ability to obtain weapons.
Mr Murphy’s call for the two votes came as presumptive Republican presidential candidate Donald Trump said he would meet with the National Rifle Association to discuss ways to block people on terrorism watch lists or no-fly lists from buying guns.
Pulse killer posted on Facebook about attack
Orlando gunman Omar Mateen apparently made a series of Facebook posts before and during his attack on a gay nightclub, raging against the “filthy ways of the West” and blaming the US for the deaths of “innocent women and children”.
The killer, whose rampage left 49 people dead, also searched for “Pulse Orlando” and “Shooting” online on the morning of the carnage and said on Facebook: “America and Russia stop bombing the Islamic state,” according to a Senate committee letter.
The messages were detailed in a letter from the Homeland Security Committee to Facebook chief executive Mark Zuckerberg asking the company to produce information on Mateen’s online activity and to provide a briefing to the panel.
Investigators also zeroed in on what role Mateen’s wife might have played in the attack at Pulse dance club.
In its letter, the committee said staffers have learned that five Facebook accounts were associated with Mateen, a 29-year-old American-born Muslim.
“The real muslims will never accept the filthy way of the West,” Mateen wrote, according to the letter.
Mateen pledged his allegiance on Facebook to the leader of Islamic State and, in his final post, warned: “in the next few days you will see attacks from the Islamic state in the usa.”