Sen. Edward M. Kennedy made clear yesterday that he will not back away from his controversial criticism of the shah of Iran but recast the question to emphasize his continuing support of President Carter' efforts to win release of the American hostages in Tehran.

The Masachusetts senator seems to have decided to sit tight for now, waiting to see what impact his remarks will have on his campaign to take the Democratic presidential nomination away from Carter.

Carter's supporters pounced Monday on Kennedy's anti-shah statements, saying they reflected bad judgment and bad timing. The Carter backers noted that Kennedy himself had previously said it would be "unwise" to discuss Iran until the hostages were freed.

In Congress yesterday, members of both parties, including House Foreign Affairs Committee Chairman Clement Zablocki (D-Wis.), criticized Kennedy's remarks, saying they might undermine the American position in dealing with Iranian militants.

A senior Democratic senator who is neutral in the presidential race expressed "shock" privately at Kennedy's comments, saying the incident created a feeling that the candidate "doesn't know a helluva lot."

Kennedy's aides said hopefully yesterday that voters around the nation might not react so dramatically. They guessed that many Americans, particularly Democrats, probably agree with Kennedy's suggestion that the shah was a repressive, corrupt dictator. And they think Kennedy can put across his point that the status of the captive Americans is an issue distinct from the shah's record as monarch.

That point is the gist of statements Kennedy has been making about Iran in campaign appearances since the interview Sunday night that prompted the to-do.

"The Iranians must know two things," Kennedy says. "First, that we will not be blackmailed -- and second, that we are not blind to the abuses of the shah."

He adds that "support for the hostages does not mean support for the shah."

These comments have drawn reasonably warm applause from audiences in Reno, Bismarck and the District in the past two days. But the statements do not address the timing of his scathing attack on the shah.

Over the past two weeks Kennedy was asked several times every day about Iran, and each time he refused to discuss the situation except for a general observation that he and other Americans were united behind President Carter in the effort to win the hostages' release.

But Sunday, in a television interview in San Franciso at the end of a 14-hour campaign day, Kennedy unleashed his atack, saying the shah "ran one of the most violent regimes in the history of mankind" and stole "umpteen billions of dollars" from Iran.

The San Francisco TV station was so unimpressed that it did not even include these remarks in the condensed interview broadcast Sunday night. But local newspaper reporters, who sat in on the taping, played Kennedy's attack as banner news and wire services quickly carried the story East.

Some reporters theorize that Kennedy deliberately ended his silence about the shah in order to stir up this turmoil, to draw a line in public between himself and Carter. The issue of Iran has overwhelmed all others in the current political dialogue and thus put a crimp in Kennedy's challenge.

On the other hand is evidence to suggest that the whole thing was simply a flub on Kennedy's part. The remark came at the end of a long day near the end of a long, tiring campaign swing. It was a sharp break with the position Kennedy held consistently over the preceding two weeks. And his staff seemed clearly unprepared for the stir their candidate created.

In any case, Kennedy seems determined now to stand by his comments on the shah and try to convince people of his new position on Iran -- that the United States should not condone the shah, hostages or no hostages.