 -- President Obama rebuked GOP presidential candidate Ted Cruz's proposal to patrol U.S. Muslim neighborhoods as a part of a counter-terrorism strategy as "un-American" and "counterproductive."

"I just left a country that engages in that kind of neighborhood surveillance, which, by the way, the father of Sen. Cruz escaped, for America, the land of the free," President Obama said, invoking Cruz's Cuban heritage in criticizing Cruz's proposal today.

Speaking at a joint news conference with Argentine President Mauricio Macri, Obama said any approach that would “single out” or “target” Muslims for discrimination “is not only wrong and un-American, but it also would be counterproductive because it would reduce the strength, the antibodies that we have to reduce terrorism.”

“One of the great strengths of the U.S. and why we haven’t seen more attacks in the U.S. is we have an extraordinarily successful patriotic, integrated Muslim-American community. They do not feel isolated,” he said.

"The notion that we would start down that slippery slope makes absolutely no sense," Obama added. "It’s contrary to who we are. And it’s not going to help us defeat ISIL."

ISIL is also known as ISIS.

The president reiterated that defeating ISIS is his top priority, saying “there is no more important item on my agenda" but that we have to go about defeating the group "in an intelligent way.”

“This is difficult work,” he said. “What we don’t do and what we should not do is take approaches that are going to be counterproductive.”

“When we see the sight of these kinds of attacks, our hearts bleed,” he said. “And it horrifies me. I have two young daughters who are growing up a little too fast. I want them to have the freedom to move and travel around the world without the possibility that they be killed. I understand why this is the top priority of the American people. This is my top priority as well.”

In the wake of Tuesday's attacks in Brussels, Cruz called for law enforcement to step up policing of Muslim neighborhoods in the U.S.

"We need to empower law enforcement to patrol and secure Muslim neighborhoods before they become radicalized," Cruz said in a statement Tuesday listing a number of count-terrorism measure.

And in addressing the criticism he’s received for pressing on with his foreign trip in the aftermath of the Brussels attacks, the president explained that part of the fight against groups like ISIS is about sending a message that “they can’t defeat us.”

“We defeat them in part by saying you are not strong, you are weak. We send a message to those that might be inspired by them to say you are not going to change our values of liberty and openness and the respect of all people,” Obama said.

“A lot of it is going to be saying, you don’t have power over us, we are strong, our values are right, you offer nothing except death,” he said.

All three Republican presidential candidates have called on the president to cut his trip short.