The Reagan administration expects Libyan leader Muammar Qaddafi to "stir up" a terrorist attack by Palestinians against American targets in the weeks ahead and has put embassies and allies on alert around the globe, officials said today.

"I would suspect over the next several weeks he's going to try to create some kind of incident and say, 'See, I did tell you,' " a senior White House official said.

The official, who has access to U.S. intelligence information, told reporters that Qaddafi also is expected to react to the conflict in the Gulf of Sidra with a claim that he chased the 6th Fleet away.

"I think he's going to push this line for all hell -- that he pushed us out of the Gulf of Sidra and he's the strong man, and Radio Tripoli will be putting that out all over the Arab world, that he kicked us out," he added.

"It will have to be bravado, because he knows damn well what happened, and he got his fingers burned, but he was smart enough to pull back so he didn't get his face blown off," said the official, who accompanied President Reagan to California for the Easter vacation.

The official's comments followed Reagan's assertion in a speech in New Orleans Thursday that the United States is aware of "intensive" preparations by the Libyan leader to hit American targets.

The remarks by the president and the senior official appeared to be part of an administration effort to prepare the American people for the possibility that Qaddafi will strike back and to warn Qaddafi against doing so.

Reagan in the past has accused Qaddafi of supporting the Abu Nidal terrorist group, which allegedly carried out the Rome and Vienna airport attacks in December.

Qaddafi will seek "to stir up, probably, Palestinians someplace -- people who are trained by Libya to take some action in some country," the White House official said.

"Now, if we're alert enough, and the host country is alert enough to protect our embassies, they'll probably come up with some godforsaken place " where "it's not going to hurt." For example, the official pointed to the incident in which someone threw a stick of dynamite on the roof of the U.S. Embassy in Bolivia.

The official said it is hard to know precisely where Qaddafi might strike, although U.S. intelligence reports before the naval exercise in the Gulf of Sidra had suggested that Qaddafi was continuing to send terrorists to European capitals to attack Americans.

"You can't tell with these people," he said. "They've got weird ideas and they try to do things on the spur of the moment."

The official would not discuss security arrangements or possible American responses to another terrorist attack. He did say, however, that "we have no plans to send the fleet back in again."

It was understood from official sources here that American allies and embassies around the world have been alerted to the prospect of a Libyan terrorist reprisal.

In Washington, Sens. J. Bennett Johnston (D-La.) and Gary Hart (D-Colo.) postponed trips to Israel, Egypt and Jordan. State Department spokesman Charles Redman said the administration asked members of Congress and their staffs to reassess Easter-week travel plans to the Middle East because of the security threat.

U.S. naval forces sunk two Libyan patrol boats in the gulf this week and damaged a Libyan surface-to-air missile site after Soviet-made missiles were fired at American planes. Although the purpose of the exercise was billed as demonstrating freedom of navigation, sources also have described it as part of a larger campaign to harass Qaddafi and destabilize his regime.

Asked whether there is evidence that Qaddafi's control over his country has been weakened by recent events, the official said it is "a little premature" to discuss that.

"That type of report doesn't come out right away, and he keeps a pretty sharp eye on who's talking to who. To get word of that out from inside his country is going to take time."

Describing the origins of the naval exercise that led to this week's conflict, the official said Defense Secretary Caspar W. Weinberger suggested maneuvers in the area because the Carter administration had canceled such exercises after Qaddafi laid claim to territorial waters in the gulf beyond the internationally recognized 12-mile limit.

Several U.S. tests were made in previous exercises, and this year's was "heightened by the fact there have been so many examples of Libyan terrorism," the official said.

"Libya has gotten stronger by purchase of Soviet arms, including the SAM [surface-to-air missile] sites. So we knew it would be more dangerous. But nevertheless we felt we had to assert our authority."