Until Tuesday, Washington entrepreneur Kirby Jones - who has served as American corporations' link to Cuba - considered himself a close associate of the newly elected government in the Dominican Republic, a friend of the president.

Then and advertisement in The Washington Post, repeated yesterday, declared that the Dominican government would have nothing to do with a conference Jones had planned here yesterday for American companies that might want to do business in the Caribbean country.

"I am the victim of a well-done sabotage effort by businessmen in the Dominican Republic who want things to stay the way they are," said Jones, charging that one of those companies is the American conglomerate, Gulf & Western Industries, the largest foreign investor in that country. In Jones' opinion, the businesses already there want to avoid the competition that new U.S. investment could bring.

Furthermore, Jones said he cancelled the proposed conference of businessmen at the suggestion of the new Dominican president, Antonio Guzman, at the time of his inaugural Aug. 16. Apparently, though, the official who placed the ad believed Jones might go ahead with his session.

Altogether, it was an unexpected first public step in Washington by the Guzman government, which is supported by the Carter administration but which followers of ex-president Joaquin Balaguer have charged is dangerously leftist and could open the country to Cuban influence.

Jones contended that although the four-column ad was under the letterhead of the Dominican Embassy, it actually was submitted by Central Bank in Santo Domingo, now run by a former official of Gulf & Western.

The Dominican Embassy, under an interim charge d'affaries, confirmed that it only was informed that an ad was scheduled and knew nothing of its content.

Jones said that the Dominican Central Bank president, Eduardo Fernandez, "is a former employe of Gulf & Western whose behavior in the Dominican Republic under former president Balaguer has been widely attacked by groups in the United States." He referred to efforts by church and other groups to show that the company had damaged the interests of the Dominican people.

"It appears that just as Gulf & Western controlled the Balaguer it may now control the Guzman government," said Jones.

Gulf & Western public relations director Fred Phillis in New York said the company knew nothing of the conference nor the ad until it appeared. He said the suggestion of influence over the Dominican government was "a ludicrous fabrication." He confirmed that Fernandez was a former employee and put the firm's investment in the Dominican Republic at about $75 million of 5 percent of overall Gulf & Western interest.

Jones said 55 American companies had agreed to attend the conference, which was arranged with Guzman and others of the Dominican Revolutionary Party after his election. The government was to be represented.

However, said Jones, when he attended Guzman's inauguration at the invitation of the party, he was told that a group of Dominican businessmen who had seen the conference invitations were resisting and he agreed to put it off.

On the day before the inauguration, he said, the Santo Domingo newspaper El Caribe headline "Lobbyist for Castro Offers to Be Middleman for New Government."

Jones heads Alamar Associates, which for 3 1/2 years had advised businesses interested in trade with Cuba. He said 250 American businessmen have visited Cuba through his efforts.

Although clearly chagrined with the outcome of the Dominican venture, Jones said he had to concede that the caper against him was artfully orchestrated.