Droves of tuned-in citizens attended the Rockville City Council meeting Monday to assure that the future of cable television in the city will not go down the tubes.

Prompted by city officials' comments in recent weeks that Rockville is not interested in cable, more than 100 persons packed the council chambers for a public hearing on whether the city should join the Montgomery County system or opt for a separate cable hook-up.

The ordinance now on Rockville's books calls for the city to award its own franchise eventually. But in recent months the county has asked municipalities to join its system and Rockville must make a decision soon. The county expects to solicit bids on a cable system in the next few months.

In May, Mayor William E. Hanna Jr. told the county that Rockville was not interested in cable. In a letter to County Executive Charles W. Gilchrist, Hanna wrote, ". . . frankly, there is a decided lack of interest in this issue (cable) at the time." In an interview Tuesday, Hanna said he signed the letter with council approval.

In a guest editorial in a local weekly newspaper, Hanna explained that he was not against cable in principle, but he said he had reservations and believed that Rockville should wait for technological improvements.

He wrote that cable could lead to the demise of commercial television and added that cable services, though exciting, are costly. In the editorial he also said he was concerned about the political implications of cable and the problem of finding a way to keep pornographic films away from children.

"There is a positive and a negative side to cable," Hanna said Tuesday. "There is no doubt that cable, or something similar, will some day come to Rockville. We have to wait and see how things go and get the best deal for the city."

But the vast majority of the 25 speakers at the 2 1/2-hour hearing said the mayor and other city government leaders do not have the right to impose their views on Rockville residents, no matter how legitimate their concerns may be.

"In our free enterprise system, if there are people willing to risk capital to offer a system and people willing to subscribe, our government should not stand in their way," said resident Terry A. Gans.

"If any council member has a personal objection, there is a simple answer: don't subscribe."

Mel Halpern, a resident of the College Gardens section of Rockville, said he had polled 263 of the 300 households in his neighborhood and found that a large number wanted cable.

"Of these 263 households, 225 signed the petition, representing a signature rate of 85.55 percent," Halpern said. "To me, this shows a definite interest in cable television -- not only in College Gardens, but also in the entire city of Rockville, of which I consider College Gardens to be a representative part."

Although the hearing was supposed to focus on whether the city should give itself the option of joining the county's cable franchise, few persons spoke to this issue.

County Cable Television Project Manager John Hansman said it would be advisable for Rockville to join the county system to assure two-way service, enabling a cable subscriber to communicate with the signal sender.

"There is no question that a more sophisticated system costs more money," Hansman said. "And it is very unlikely that Rockville, as a stand-alone system, will receive the two-way capability."

The council left the issue open for three more weeks. Written comment should be sent to the city clerk, City of Rockville, Maryland at Vinson, Rockville, 20850.