"I proudly serve in this administration, and I enthusiastically support most of its decisions and the direction it is taking the country," Haley stated. "But I don't agree with the president on everything."
Commenting on her plans, Haley stated she would not be running for the White House in 2020, but would campaign for Trump.
"We're all happy for you in one way, but we hate to lose (you)…. Hopefully, you'll be coming back at some point. Maybe a different capacity. You can have your pick," Trump said.
READ MORE: US Envoy to UN Nikki Haley Lashes Out at EU's Mogherini Over Iran
According to the US president, Haley told him about her impending resignation six months ago. Trump added that he was considering several candidates for Haley's job and that the next US ambassador would be named in two or three weeks.
Haley, 46, was governor of South Carolina and the first woman to hold the post. In 2017 she was named the US envoy to the United Nations.