In a modest political "cattle show," five Republican presidental hopefuls addressed the nation's Republican governors here tonight, but most of the governors were unmoved.

"I've heard it all before," said Illinois Gov. James R. Thompson, "and I'll hear it all again." Like most of the governors gathering here for their annual meeting, including Virginia Gov. John N. Dalton, Thompson said he was uncommitted and intended to remain so for now.

Almost all of the nation's 18 Republican governors were on hand for the addresses by Republican hopefuls John B. Connelly, Sen. Howard H. Baker Jr., Sen. Larry Pressler, Benjamin Fernandez and the indefatigable Harold Stassen, who has been running for president every four years since 1948.

Connally the former governor of Texas and former treasury secretary, seemed to gather the most applause and the most enthusiasm of the five, which was a rather limited accolade considering the absence of Ronald Reagan and George Bush.

At a news conference and in his remarks to the assembled governors, Baker the Senate minority leader, said he talked today with President Carter and Secretary of State Cyrus R. Vance about the Iranian crisis. Baker told the governors that the prospect of American Embassy hostages in Iran being put on trial "is totally unacceptable to me" -- applause -- "and it should be to the government of this country that we should stand by and see these American citizens tried in Iranian courts in these circumstances."

On a domestic topic, Connally called for the use of high-sulfur coal from Midwestern states -- a key issue in such places as Illinois, Ohio and West Virginia -- and said he would like to amend federal air pollution standards restricting the use of high sulfur coal. He said that he believes the worst environment "is to be cold and hungry and unemployed."

The Republican governors are meeting here at the invitation of Gov. William P. Clements, the first Republican governor in Texas in 105 years. wThey expect to take up a series of predictable resolutions over the coming two days, including one on energy that is expected to be critical of President Carter's energy policy.

Connally, a former Democrat, noted that a few years ago such a gathering of Republicans would not have occurred in Texas because of the Democrats' longstanding hold on state offices. He called on Republicans to take the message to American voters that Democrats are responsible for inflation, deficit spending and the failure to develop a national energy policy.

Outside of the Baker and Connally appearances there was scant political excitement today, and several governors said there was little presidental politicking between candidates and the governors.

The governors gave a warm reception to candidate Fernandez, who told them that the United States must improve its relations with energy-rich Mexico. "What better way to do that than with a Fernandez in the White House?" he asked.

Former secretary of state Henry A. Kissinger is to address the governors at the closing session of the two-day conference.

"We hope to give everyone an idea what the governors are doing in these critical areas compared to what is not happening at the national level," said Ralph Griffith, executive director of the Republican Governors Association.

Gov. Otis R. Bowen of Indiana will open the first general session, expected to attract about 800, Monday morning. A panel, "Energy: What the States Are Doing," will feature Govs. Lamar Alexander of Tennessee, William P. Clements of Texas, John Dalton of Virginia and Pierre S. du Pont of Delaware.

Gov. Richard Thornburgh of Pennsylvania will tell of his experiences during the Three-Mile Island nuclear emergency.

Former president Gerald Ford is to speak Monday afternoon followed by a panel on fiscal responsibility that features Govs. Albert Quie of Minnesota, Lee Dreyfus of Wisconsin, Charles Thone of Nebraska and Richard Snelling of Vermont.