WASHINGTON -- Democratic presidential front-runner Hillary Clinton lobbed some not-so-veiled criticism at Republican counterpart Donald Trump on Monday, challenging the billionaire's foreign policy credentials in front of a high-profile confab of pro-Israel activists assembled here.

Without mentioning the fellow New Yorker by name, the former secretary of state repudiated Trump's past remarks on immigration, Muslims and white supremacist David Duke, indicating they were not in line with Jewish values during a more than 30-minute speech at the American Israel Public Affairs Committee’s annual policy conference.

We've had dark chapters in our history before. We remember the nearly 1,000 Jews aboard the St. Louis who were refused entry in 1939 and sent back to Europe. 

But America should be better than this, and I believe it's our responsibility as citizens to say so. If you see bigotry, oppose it. If you see violence, condemn it. If you see a bully, stand up to him."

Clinton also renounced Trump's recent remarks that he would stay neutral while brokering Israeli-Palestinian peace talks should he become president:

"I feel so strongly that America can't ever be neutral when it comes to Israel's security or survival. We can't be neutral when rockets rain down on residential neighborhoods, when civilians are stabbed in the street, when suicide bombers target the innocent. Some things aren't negotiable, and anyone who doesn't understand that has no business being our president."

The real estate mogul has since clarified his comments and support for Israel, but his initial remarks have raised the eyebrows of many in the Jewish community and prompted pointed attacks from his GOP rivals, particularly Texas U.S. Sen. Ted Cruz.

Trump will address the gathering of Jewish activists Monday evening, along with fellow Republican presidential candidates Cruz and John Kasich.