A group of U.S. businessmen in Libya, responding to a government invitation, expressed public disagreement here tonight with the Reagan administration's decision to call them home because of what Washington calls a threat to their safety.

Their remarks, at a reception organized by Libya's equivalent of a foreign ministry, were part of a visible effort by Col. Muammar Qaddafi's government to depict assertions by the administration about danger to Americans here as unfounded exaggerations.

The approximately 20 American business executives, most of whom are here with U.S. oil companies or related firms, supported the Libyan effort. Although they barred use of their names or company affiliation, the Americans scoffed at the idea they could be in danger and expressed reluctance to leave high-paying jobs to Canadians and Europeans, who they expect will quickly replace them.

The Reagan administration cited "imminent danger" to the 1,500 Americans resident here as one reason for its decision Thursday to order them out of Libya and bar travel here by U.S. citizens. Officials in Washington indicated they had in mind the possibility of a hostage seizure similar to that in Iran in November 1979.

In response, the official Libyan news agency JANA issued a statement yesterday denying Americans here run any such risk and pledging the Qaddafi government's help to any who want to leave. Ahmed Toumi, an official of Qaddafi's Foreign Information Department, repeated the denial tonight, adding:

"Many of them don't want to leave. They make good money. And they say it is safer than New York. Some were on Libyan television last week. They complained about Libyan food only. But I can understand that."

To back up the point, the Peoples Bureau for Foreign Liaison, formerly the foreign ministry, organized the reception tonight at a hotel where government officials were directing foreign journalists arriving for a news conference they said was scheduled by Qaddafi. The ministry invited American businessmen to attend, drove them to the hotel and had information officials encourage journalists to ask the businessmen how they felt about leaving.

"We did it for you guys," said Libya's secretary for heavy industry, Omar Mustafa Muntasser, in a conversation with correspondents.

Despite their reluctance, some of the American executives said they will be pulling out soon because of orders from their employers. But others complained they are unable to send their children home for Christmas vacation as usual because of fears they would be unable to return.

In Rome, a common departure point for Libya-bound flights, the U.S. Embassy has asked the Italian national airline, Alitalia, to refuse passage to U.S. passport holders traveling to Libya, airline officials said. But after informing Americans of the embassy's request, officials allowed several to continue on their way to Tripoli today.

The businessmen, most from company headquarters in Tripoli, predicted Libyan oil production will be affected little in the short run even if all the Americans were to leave. One Canadian oil worker said the best method to exercise pressure on Libya would be to "cordon off Houston" to prevent export of spare parts for drilling equipment, most of which he said come from the United States.

About 20 U.S. companies, including a half dozen oil firms, operate here. They already employ many non-Americans, company officials said. Toumi contended that, as a result, U.S. companies probably can continue to operate even without American personnel.

But by all appearances, the mood in Tripoli is not confrontational, anyway. Libyan officials went out of their way to greet visiting U.S. journalists, organizing a dinner with traditional dances to entertain those awaiting Qaddafi's appearance at the news conference.