"This is not the outcome we wanted or we worked so hard for and I'm sorry that we did not win this election for the values we share and the vision we hold for our country," she said.
"This is painful, and it will be for a long time, but I want you to remember this: our campaign was never about one person or even one election."
The constitutional democracy, Clinton added, "enshrines the peaceful transfer of power, and we don't just respect that, we cherish it."
"It enshrines other things too," she said.
Taking a slight jab at Trump, Clinton went on to explain: "The rule of law, the principle that we are all equal in rights and dignity, freedom of worship and expression. We respect and cherish these values, too, and we must defend them."
US president Barack Obama, meanwhile, vowed to ensure a smooth transition for Trump at a speech at the Rose Garden of the White House.
Said Obama, "We are Americans first. We're patriots first. We all want what's best for this country." – with reports from the Agence France-Presse/Rappler.com