Syrian President Hafez Assad today abruptly postponed a state visit to Czechoslovakia as presidential aides expressed "displeasure" with the Reagan administration's perceived lack of gratitude for his crucial role in freeing the American hostages in Beirut.

The aides specifically mentioned "certain U.S. government statements" as well as the "general Mideast situation" in explaining why Assad again postponed the visit to Prague originally scheduled for 10 days ago.

Last Wednesday, the Syrian government took the unusual step of announcing that the visit was rescheduled for July 2 in a move widely interpreted here as signaling his determination to solve the hostage crisis by then.

Neither the U.S. Embassy nor the Syrian government commented on the mid-morning visit that American Ambassador William Eagleton paid to the Foreign Ministry. But late tonight, a presidential aide said, "We do not want to beg for gratitude." Another said, "It would be humiliating to say we are disappointed" because "we did not do what we did" on the hostages' behalf "to get thanks. But you can say that we are displeased."

European diplomats said President Reagan even waited until the U.S. Air Force plane carrying the hostages to West Germany was out of Syrian airspace before sending what they described as a perfunctory message of thanks lumping Assad's role with that of Algeria and arch-rival Jordan.

A number of ordinary Syrians contrasted the administration's attitude with the seemingly enthusiastic and spontaneous thanks that the hostages expressed, during their Damascus news conference, for Syrian help in freeing them.

Western diplomats also questioned the administration's tactics in light of the president's proclaimed determination to enlist Syrian help in obtaining the release of seven Americans kidnaped in Lebanon before the June 14 hijacking of the TWA airliner.

"You'd think someone back in Washington would realize you catch more flies with honey than vinegar," a diplomat said.

In Washington, Secretary of State George P. Shultz told a television interviewer on Monday: "We are very glad that President Assad and Syria did what they did. We hope we can build on that. We hope they will help us to get the other seven out."

But at the State Department news briefing, spokesman Bernard Kalb said under questioning that Syria remains on the list of countries supporting terrorism "because, according to reliable reports, a number of terrorist organizations have received some form of support from Syria . . . or have training facilities there or in parts of Lebanon under Syrian control." Kalb said removing Syria from the list "is not under consideration at this time."