Sen. Jesse Helms of North Carolina, a leading spokesman for conservative Republicans, has accused the managers of the Republican platform committee of using "hardball" tactics to deny a voice to him and other conservatives.

In a telephone interview from his North Carolina home, Helms said he had learned that his bid to appear before the platform committee when it holds its final hearings in Detroit this week has been turned down.

Helms also said that someone from the Republican National Committee staff had canceled a room reservation at Detroit hotel for a reception he and other North Carolinians planned to give today for the platform committee members.

Helms said he was trying to "straighten out" the problem with Sen. John G. Tower of Texas, the platform committee chairmen, but added: "If they're going to play hardball, we will respond."

Tower, reached in Detroit, noted that Helms had already testified at a regional hearing and that no senators other than the GOP leaders would appear as closing witnesses.

"If Gov. Reagan wants anybody on as his witness, all he has to do is let me know and we'll put them on, anyplace in the program he wants," Tower said.

Operatives for prospective nominee Ronald Reagan on the platform committee had made no such request, he said.

A Helms associate indicated that the senator had sought to appear on his own behalf to advance Reagan's positions.

The North Carolina senator conducted his own battle on platform issues at the 1976 GOP convention and apparently is ready to do so again, whatever the wishes of Reagan's managers.

"My only concern," Helms said, "is seeing that Reagan's positions are reflected in the platform."

While the draft platform has not been made public, Helms said that the last version he saw before leaving Washington failed that test "in several important areas."

Helms said Reagan had "made it very, very clear where he stands on ERA [the Equal Rights Amendment], but the platform draft is absurdly rhetorical and unclear."

Reagan has opposed the ERA, while supporting state laws to protect women's rights. Yesterday, however, some key Reagan aides here said Reagan might not insist on removal of pro-ERA language that has been in Republican platforms since 1940.

Helms said his other areas of concern were the abortion plank, where, he said, "We need to toughen the language"; diplomatic treatment of Taiwan, where, he said, "We have to make it clear Peking will not dictate our relationship," and the trade plank, where, he said, "Our first commitment to American jobs must be stressed."

Helms' aide said they were angry that he was being denied status as a closing witness, while that privilege was being given to such prominent officials of the Ford administration and 1976 Ford supporters as former secretary of state Henry A. Kissinger, former secretary of defense Donald Rumsfeld, Michigan Gov. William G. Milliken and Rep. Guy Vander Jagt of Michigan.

"The Ford people are taking over the Reagan campaign," one Helms associate said. "And now it looks like they're taking over the platform as well."