US President Donald Trump on Tuesday decried anti-semitic threats targeting Jewish community as "horrible" and "painful", saying that there is need to fight bigotry, intolerance and hatred in all of its very ugly forms.

"This tour was a meaningful reminder of why we have to fight bigotry, intolerance and hatred in all of its very ugly forms," Trump said after his maiden visit to the National Museum of African American History and Culture in Washington.

He said the "anti-semitic threats targeting our Jewish community and community centers are horrible and are painful and a very sad reminder of the work that still must be done to root out hate and prejudice and evil."

His remarks came in the backdrop of increasing threats against Jewish community and community centers in the US.

"Etched in the hall that we passed today is a quote from Spottswood Rice, a runaway slave who joined the Union Army. He believed his fellow African-Americans always looked to the US as the promised land of universal freedom," Trump said.

"Today and every day of my presidency, I pledge to do everything I can to continue that promise of freedom for African-Americans and for every American. So important, nothing more important," the president said.

Describing his tour to the museum as comprehensive, Trump promised to work for the African-American community.

"We're going to do great things in our African-American communities together," he said with his nominee for Housing and Urban Development, Dr Ben Carson, standing by his side.

"Ben's going to work with me very, very closely. And HUD has a meaning far beyond housing. If properly done, it's a meaning that's as big as anything there is. And then we'll be able to find that true meaning, and the true meaning of HUD as its secretary," he said.

Trump also read out a quote from Martin Luther King Jr.

In 1955, King Jr told the world, "We are determined to work and fight until justice runs down like water, and righteousness like a mighty stream," Trump said.

"And that's what it's going to be. We're going to bring this country together. Maybe bring some of the world together, but we're going to bring this country together," he added.

"We have a divided country. It's been divided for many, many years, but we're going to bring it together. I hope every day of my presidency, we will be honouring the determination and work towards a very worthy goal, and for Lonnie and David and David and Ben and Alveda and everybody, I just want to — I just have to say that what they've done here is something that can probably not be duplicated," Trump said.

Trump's daughter Ivanka and Senator Tim Scott were also present on the occasion.