Democratic Party Chairman John C. White said yesterday that Senate Majority Leader Robert C. Byrd (D-W. Va.) acted without fully thinking in calling for an "open" national convention in New York City next week.

In the latest salvo in an increasingly nasty intraparty war over the open convention issue, White said that Byrd "is an expert on Senate rules, but . . . I don't believe the senator is familiar with the history of the rules in the development of this party."

"I don't believe the senator fully understood the implication of what he suggested," White said on "Meet the Press" (NBC, WRC).

Byrd became the most prominent Democrat to support the open convention movement when he announced on Saturday his opposition to a proposed rule that would require delegates to vote for the candidate they were elected to support in their state primaris or caucuses. Such a rule would assure a first ballot victory for President Carter, who won a clear majority of the 3,331 delegates in those contests.

Proponents say opening the convention would unite the party, but White said yesterday he believes the true purpose of the drive is to dump Carter from the 1980 Democratic ticket.

"I don't have any doubt whatsoever that it is a 'dump Carter'" movement, White said, but he mentioned no names in connection with that belief.

That opinion apparently is shared by Carter, who reportedly voiced that belief in a telephone conversation with Edward Bennett Williams, a prominent Washington lawyer who is the chief spokesman for the open convention advocates.

Williams, in an appearance on "Face the Nation" (CBS, WDVM), said he discussed the issue with Carter last Thursday. Carter said he believed the open convention proponents are trying to move him out of office, Williams said.

"He said he thought that the group . . . had many people who wanted a candidate other than himself to be nominated. I couldn't speak to that," said Williams, who insisted that he and his associates in the drive are "religiously neutral" on the question of the nominee.

Williams accused Carter of trying to get the delegates to "vote themselves into slavery."

"I do not understand, I really do not understand why the president and his advisers are so fearful of letting their delegates vote their preference," Williams said.

In his conversation with the president, which he charaterized as "very pleasant," Williams said that Carter "told me why he's in favor of the rule. I told him why I was opposed to the rule."

Williams was instrumental in passing at the 1974 Democratic mini-convention in Kansas City a provision in the Democratic Party constitution that "I regard as a bill of right -- that no delegate to any convention of the Democratic Party should ever be required to vote other than his preference."

Carter "didn't agree with that," Williams said.

Meanwhile, the issue was in the forefront at the opening of the annual meeting of the National Governors Association in Denver.

New York Gov. Hugh Carey, one of the original proponents of the open convention, said when he arrived there last night that he was "not here to start a fight," but still believed it would be wise for Carter and Sen. Edward M. Kennedy (D-Mass.) to release their delegates.

Carey said he thought there was "a tendency to overkill" on the part of Carter lieutenants battling against the rule change and he gibed at the president's efforts to solidify his delegates' loyalty by inviting them to the White House.

Noting that Carter lieutenants say that repeal of the rule would lead to a brokered convention in smoke-filled rooms, Carey said, "The last time I looked, the smokers and brokers were all in the East Room of the White House."

[In Medford, Mass., Kennedy said his own survey of delegates shows they will vote in favor of an open rule. "I believe we'll have an open convention and our surey shows that," he said.]

Earlier yesterday in Denver, Gov. Richard D. Lamm, host for the governors' conference, said he also supported the call for an open convention.

"Right now, I think there's every indication that Jimmy Carter wouldn't be our strongest candidate," Lamm told reporters at a news conference. Lamm said, however, that he would not actively seek support for his position from his Democratic colleagues at the session. Thirty of the 50 state governors are Democrats.

Lamm would be unsuccessful if he did seek such support, according to Eugene Eidenberg, a presidential assistant attending the convention.

"Dick Lamm hasn't been comfortable with this administration from the beginning," Eidenberg said. The Colorado governor's comments "have no influence among the governors," he said.

Robert S. Strauss, Carter's campaign chairman, also was expected at the convention to help shore up support for the president.