Sen. Robert Morgan (D-N.C.) was robbed of $300 by three teen-agers Tuesday night, three blocks east of the White House, D.C. police reported yesterday.

Officials said Morgan was window-shopping in front of the Doubleday Bookstore at 1331 E Street NW when he was approached and surrounded by three teen-agers at 10:15 p.m. They said one of the youths wielded a shaving kit with something "pointed" sticking out of the end, and told Morgan to hand over hand over his wallet.

As he gave the youth his wallet, Morgan asked to have his credit cards back, police said. After hesitating briefly, the youth returned the wallet and credit cards after taking $300 in cash, officials said.

They said the youths fled east on E Street NW.

According to Morgan's press secretary, Bob Jackson, the senator had just left a meeting with North Carolina agriculture officials at the Washington Hotel on 15th Street and Pennsylvania Avenue NW, and was strolling and window-shopping when he was approached by the youths.

Jackson said the senator, who was along was unhurt in the robbery, and that the incident was over in "a matter of seconds."

"There were apparently a lot of people on the street at that time, waiting for cabs and such, and the robbery was within sight of several sidewalk cafes," Jackson said. He said that after the robbery, Morgan "hollered something," and several bystanders started "yelling stuff like, 'stop thief' and 'get their description.'"

According to Jackson, Morgan went to the National Theater at 1321 E Street NW after the holdup to use a pay telephone to call the police, but found he had only a nickel.

"The senator went back to the street and started asking people for a dime." Jackson said, "and all of a sudden about 20 people offered him one."

Since succeeding former Senator Samuel J. Ervin three and half years ago, Morgan and his staff of 16 assistants have suffered 13 robberies in Washington, including eight armed robberies, four home burglaries and one car theft, Jackson said.

Morgan, who is a member of the Senate's banking, housing and urban development, ethics, and intelligence committees, could not be reached for comment yesterday.

"He had a restless, sleepless night Tuesday," Jackson said. "He alternated between being angry and being reconciled to the fact that he was lucky to have escaped with his life."