CIA Director William J. Casey made a secret visit to Damascus early this month to discuss release of the Rev. Lawrence M. Jenco and other U.S. hostages with Syrian President Hafez Assad, administration sources said yesterday.

The sources confirmed a copyright story in the San Francisco Examiner that quoted "an intelligence source" as saying Casey had made the trip to Syria and helped bring about the release of Jenco. The Examiner account said the trip was so secret that only President Reagan and three key advisers knew of Casey's mission.

Sources who discussed the trip with The Washington Post said Casey had tried to gain Assad's help in winning release of Jenco and three other U.S. hostages held by Islamic Jihad, a pro-Iranian Shiite terrorist group. One source speculated that Jenco, a 51-year-old Roman Catholic priest from Joliet, Ill., was set free because he suffers from a heart condition.

The CIA declined comment, with a spokesman saying that the director's travels are never discussed by the agency.

President Reagan telephoned Jenco in Wiesbaden, West Germany, yesterday afternoon and talked with him for seven minutes. He said he was "touched and pleased" by Jenco's expressions of concern for the three hostages held with him.

"Our prayers for your release have finally been answered," a White House statement quoted Reagan as saying. "The patient and persistent efforts of so many people have been successful. As happy as I am that you now have your freedom, I will not be satisfied until all our citizens are released from captivity. I know that you join me in these sentiments."

Administration officials have declined to go into detail about the Syrian role, if any, in securing Jenco's release. Vice President Bush and Assistant Secretary of State Richard W. Murphy have said that Syria assisted in the transport of Jenco to freedom but have repeatedly declined to answer other questions about the Syrian role, Washington Post staff writer David Hoffman, traveling with the Bush party in Israel, reported.

Sources who confirmed Casey's travels said he also discussed the issue of Syrian-Israeli military tensions with Assad and visited several Western European capitals on the same trip.

The Examiner account said that Vernon A. Walters, the U.S. ambassador to the United Nations, had made several similar trips to Damascus to meet with Assad and is believed to have had a hand in freeing Jenco. The priest was found on a road in the Syrian-controlled southern Bekaa Valley early Saturday.

Jenco reported that three other Americans held captive with him were in good health. They are Terry Anderson, 38, the chief Middle East correspondent for The Associated Press; David Jacobsen, 55, administrative director of American University Hospital in Beirut; and Thomas Sutherland, 54, dean of agriculture at American University.

Another American kidnap victim, William Buckley, 57, former political officer at the U.S. Embassy in Beirut, was reported executed by a pro-Iranian extremist group last October, but his body has never been found.

In a videotape brought out by Jenco, Jacobsen appealed to Reagan to negotiate the release of the remaining hostages. Reagan has consistently said that U.S. officials were willing to talk to the captors of the Americans but would not negotiate with them. White House spokesman Larry Speakes yesterday reiterated this policy in response to questions about Jacobsen's appeal.