Republican presidential hopeful Sen. Rand Paul said he is "appalled" that the National Security Agency's surveillance of Israeli Prime Minister Benjamin Netanyahu also resulted in the NSA capturing private communications of U.S. lawmakers.

"I'm appalled by it," Paul said on Fox News' "Fox & Friends" on Wednesday. "You could see how it would stifle speech if you're going to eavesdrop on congressmen, and that it might stifle what they say or who they communicate with."

The Kentucky senator was responding to a Tuesday report from The Wall Street Journal that revealed that, despite President Obama promising to stop spying on allies two years ago, the NSA continued spying on Netanyahu out of fear that he would derail the Iran nuclear deal. While eavesdropping on Netanyahu and other allies, the NSA also collected private conversations of members of Congress and American-Jewish groups and learned that Netanyahu and advisers had leaked negotiation details.

"This is exactly why we need more NSA reform and the debate in Washington right now has been unfortunately going the other way since the San Bernardino shooting. Everyone's saying 'Oh we need more surveillance of Americans.' In reality, what we need is more targeted surveillance. I'm not against surveillance, but I am against indiscriminate surveillance," Paul said.

"And also this is not unusual... that when we listen in on foreigners' conversations when they're talking to Americans, that we're scooping up tens of thousands of conversations of Americans."

He continued: "This is a real problem because it's a real invasion of our privacy. We absolutely need more controls on the NSA and more controls on our intelligence agencies."

Sen. Marco Rubio, a presidential rival who has often butted heads with Paul and other libertarian-leaning Republicans on the issue of spying, suggested that critics should exercise caution before condemning the Obama administration for the surveillance, reported CNN.

"I want to be very careful, I'm a member of the (Senate) Intelligence Committee, so obviously I want to be very careful about what I say about information of this kind," Rubio said Wednesday on "Fox & Friends." "Obviously people read that report they have a right to be concerned about it this morning. They have a right to be concerned about the fact that, while some leaders around the world are no longer being targeted, our strongest ally in the Middle East, Israel, is. These are all concerns and they're legitimate."