In an effort to bring television viewers a greater variety of programs, the Federal Communications Commission voted unanimously yesterday to relax its rules for over-the-air pay television.

In lifting the 14-year-old restrictions on pay television, the commission said it hoped the number of pay-TV stations would increase across the country, especially in moderate-sized cities that are now served by several regular television stations.

The commissioners said that the current rules, which, among other things, permitted pay-TV stations only in cities that had at least four commercial television stations, hampered the growth of the industry.

There are 27 pay-TV stations now on the air, including one in Washington, Super TV, which broadcasts on Channel 50. Another 16 have received permission to begin operations, and applications for 30 more stations are pending.

FCC officials predict that as many as 30 more pay-TV stations could be created by yesterday's decision.

"This is another step at eliminating a lot of regulatory underbrush grown up that has been made anachronistic by technology and a turn of events," said FCC Chairman Mark S. Fowler.

The decision affects pay television stations that typically broadcast a signal that all area viewers can receive during the day and a scrambled signal at night. Subscribers who pay a monthly fee for a decoder can receive the signal, which generally broadcasts movies and sports events without commercials.

The FCC also eliminated its requirement that any pay-TV station broadcast at least 28 hours a week of conventional programming.