WASHINGTON — Regulators are taking another crack at their effort to keep the web free and open, introducing new rules that would discourage Internet service providers from charging companies to stream their movies, music and other content through a faster express lane.

The proposal, unveiled by the Federal Communications Commission on Wednesday, is part of a continuing battle over the basic pipelines through which information flows on the Internet. With the latest plan, the F.C.C. is hewing close to previous efforts — albeit with some technical differences — with rules that would prevent Internet service providers from blocking any legal sites or services from consumers and would aim to restrict, but not outlaw, discrimination.

Broadband players like Verizon and Time Warner Cable have spent billions of dollars upgrading their infrastructure, and they argue that they should manage their networks as they like. They are pushing, for example, to give Netflix, Amazon and other content providers faster access to their customers at a cost.

But regulators want to prevent such deals, saying large, rich companies could have an unfair advantage. The worry is that innovation could be stifled, preventing the next Facebook or Google from getting off the ground. Consumer advocates have generally sided with regulators in the belief that Internet providers should not give preferential treatment to content companies willing to pay extra — a cost that could be passed on to customers.