Israeli President Reuven Rivlin expressed shock Wednesday over anti-Semitism at a recent US white supremacist rally, but said American leaders would succeed in dealing with "this difficult challenge".

Rivlin wrote to the Conference of Presidents of Major American Jewish Organizations to convey his "support and solidarity for the American Jewish community" after the unrest in Charlottesville.

"The very idea that in our time we would see a Nazi flag -- perhaps the most vicious symbol of anti-Semitism -- paraded in the streets of the world's greatest democracy, and Israel's most cherished and greatest ally, is almost beyond belief," he said.

"We have seen manifestations of anti-Semitism again and again arise across the world; in Europe and the Middle East.

"I know that the great nation of the United States of America and its leaders will know how to face this difficult challenge, and prove to the world the robustness and strength of democracy and freedom," the Israeli president said.

Rivlin's remarks came a day after Prime Minister Benjamin Netanyahu condemned "neo-Nazism and racism" in the Virginia college town, a condemnation that came only after US President Donald Trump denounced racism while calling the Ku Klux Klan and neo-Nazis "repugnant".

Other Israeli officials, including Education Minister Naftali Bennett, had issued condemnations earlier.