The United States voiced increased confidence yesterday that Iranian Premier-designate Shahpour Bakhtiar will be able to put together a new civilian government and win parliamentary approval of it by next week.

The State Department said it now appeared possible that the former oppposition leader would present his cabinet to the shah today.

"It is therefore possible that there could be a formal parliamentary ratification by early next week," spokesman Hodding Carter said.

He cautioned, however, that this was not certain.

Other officials said it remains to be seen whether a Bakhtiar government -- or any government -- could effectively deal with the turmoil at this time.

But these assessments, based on reports from the U.S. embassy in Tehran, signaled a shift from the skepticism widely voiced in the administration earlier this week that Bakhtiar had less than a 50-50 chance of putting together a government.

The State Department changed emphasis Thursday by saying it would cooperate fully with the new Bakhtiar government once it was in place.

Most U.S. aides now believe that Shah Mohammad Reza Pahlavi will leave Iran for a vacation after a new government takes office.

But spokesman Carter said the shah had not disclosed his plans to the United States.

"I can't say anyone has a sense of when, how and whether the shah's travel plans will evolve," he said.

Asked if the U.S. offer of cooperation would hold whether the shah stayed in or left Iran, spokesman Carter said: "We're willing to cooperate with the government which is established within the constitutional framework of Iran (which calls for a monarchy). I'm not going to speculate on what people do or do not do."

The State Department spokesman confirmed that U.S. Air Force Gen. Robert Huyser. deputy commander of American forces in Europe, had arrived in Tehran Thursday on a tour that will take him to Saudi Arabia.

The spokesman would not deny published reports Huyser had been sent to urge calm among the Iranian armed forces.

Huyser was to confer with U.S. ambassdaor to Iran William Sullivan and others before leaving today for Saudi Arabia.

United Press International reported from Washington that Huyser would try to assess whether top secret U.S. military and surveillance equipment should be moved out of the country if a leftist government takes power, according to sources.

Iran has received more than $8 billion in sophisticated U.S. weapons in the last six years, including F14 fighter planes with Phoenix missiles.

Defense sources quoted by UPI said that Huyser would also examine the influence that Iranian military leaders are likely to hold in the new government.