"When I see the president do this, you know, as someone who's been around a while, I saw Ronald Reagan. Ronald Reagan didn't do this. George W. Bush, his dad [George H.W. Bush], none of them did it," Williams said. "Why does Donald Trump think that this is good? It divides the country."
Co-host Jesse Watters began to talk over Williams, who asked to finish his point.
"All of us sitting here might have some strong opinion," he said. "But the president of the United States hammering this culture wars issue to his political benefit is expedient and does not -- this is a guy who was pro-choice for most of his life."
Trump became the first sitting president to address the annual rally in Washington, appealing to the anti-abortion movement with a call to protect the sanctity of life while accusing Democrats of becoming more "radical" on the issue.
Co-host Greg Gutfeld jumped in to argue that the pro-choice view of abortion was once considered "middle of the road," but that had changed.
"Pro-choice has changed so much that if you voice any of the slightest thought that late-term abortion is bad, you are wrong," Gutfeld said. "Pro-choice has changed to such an extreme level that you have to run out there and exclaim that abortion is great."
Williams argued it was the opposite, saying: "Republicans used to be big advocates of family planning until you got into a situation where they saw there was some political benefit to it."
Fox News' Tyler Olson contributed to this report.