FCC Chairman Ajit Pai is skeptical of state efforts to preserve net neutrality rules, saying Monday that the internet "has to be regulated by the federal government."

More than two dozen states have sued the FCC or proposed their own internet regulations to reinstate the Obama-era rules, which required internet service providers to treat all internet traffic as equal. The FCC voted in December to repeal the 2015 Open Internet Order. The rules formally expired Monday.

"What we're going to do is take a look on a case-by-case basis at each state law and determine the right course, but at a broad level, the internet is inherently an interstate service," Pai told CNBC's "Squawk Alley" Monday. "We don't [want] every one of the 50 states and however many local jurisdictions to have a bite of the regulatory apple."

The repeal has prompted a backlash from top executives at companies such as Facebook and Amazon, as well as Democratic lawmakers.

Republicans have argued that forcing internet service providers to treat all traffic equally will curtail ISPs' incentive to invest in infrastructure upgrades and stifle innovation that would bring consumers better service.

But the other side, including most internet content companies and many Democrats, believes that if ISPs are not explicitly banned from treating different internet traffic in different ways, they will use this power to charge higher rates for certain types of traffic, stifling the free flow of information in order to bolster their profits.

Pai said in the event of anti-competitive conduct, the FCC and Federal Trade Commission will have to become the "cops on the beat."

The Senate last month voted in favor of keeping the net neutrality rules from the Obama era, but the measure is unlikely to be approved by the House of Representatives.

—CNBC's Anjali Robins contributed to this report.