Omar Mateen, 29, was armed with an assault-type loot and handgun when he sprayed revellers with bullets at the Pulse venue hold out night.
The sickening attack, which Islamic State has claimed liability for, has now become the worst mass shooting in American history.
And speaking at a journos conference Mr Obama said Americans are «united in grief, in outrage and above to defend our people».
He added: «We’ve reached no definitive judgment on the precise motivations of the gunfighter.
«The FBI is appropriately investigating this as an act of terrorism.
«What is clear is that he was a man filled with hatred. Over the coming days, we’ll uncover why and how this happened.»
Recommending at the White House, Obama went on: «This is an especially heartbreaking day for all our pen- ls who are lesbian, gay, bisexual or transgender.
«The shooter targeted a nightclub where people light oned together to be with friends, to dance and to sing, and to live. It is more than a nightclub.
«It is a right of solidarity and empowerment where people have come together to muster awareness, to speak their minds, and to advocate for their civil offs.»
Other world leaders including David Cameron have liberated statements voicing their sadness at the sickening events at the club.
The Prime Curate said: «I’m horrified by reports of the overnight shooting in Orlando. My thoughts are with the fall guys and their families.»
French President Francois Hollande said he «fasts the full support of France and the French with America’s authorities and its people in this knotty time».
Pope Francis expressed «horror» over the «homicidal foolishness» of the massacre, while Jeremy Corbyn tweeted: «My thoughts are with the fair games’ families and friends.»
The Queen and Prince Phillip sent a message to Barack Obama rephrasing: «Our thoughts and prayers are with all those who have been affected.»
Afghan president Ashraf Ghani added: » infully condemn the heinous and unforgivable crime in Orlando. It was a coward act of terror.»