A Dade County circuit jury convicted Mercury Morris on cocaine trafficking, conspiracy and possession charges yesterday in Miami.

Morris, formerly a star running back with the Miami Dolphins, stood expressionless as the verdict was read. A jury of two women and four men deliberated about three hours before reaching a verdict.

"I feel bad for you, Merc," Circuit Judge Ellen Morphonios Gable told Morris. "I'm just sorry." Gable set sentencing for Jan. 20, then Morris was led off by police.

The jury found Morris guilty on one count of trafficking in cocaine, one count of conspiracy to traffic in cocaine and two counts of possession. The trafficking conviction carries a mandatory penalty of at least 15 years in prison and he could be sentenced to 40 years.

The jury acquitted him on two counts of selling cocaine.

Earlier, Gregory Victor, an assistant state attorney, told jurors that Morris should be found guilty because, "he sold, he delivered and he possessed."

Victor said Morris intended to make drugs a regular business, and reminded the jury of tapes that recorded Morris saying he wanted his customers to come back "again and again and again."

Earlier in the day, Morris' lawyer said that his client had rejected a plea bargain that was accepted by two codefendants.

The lawyer said Morris would let the jury decide his fate.

The codefendants pleaded guilty to charges of drug trafficking and conspiracy in exchange for the prosecution's recommendation that the mandatory minimum sentence, 15 years in prison, be waived and that the defendants remain free on bond until sentencing . . .

A federal judge in Philadelphia dismissed a $148 million antitrust suit against the NFL filed by a group that tried unsuccessfully to get a franchise. An attorney for the businessmen who wanted to operate the Mid-South Grizzlies said his clients would appeal. U.S. District Judge Joseph L. McGlynn Jr. told the plaintiffs to form their own league . . .

In Baltimore, police seized $125,000 worth of suspected cocaine and marijuana, guns and cash in a raid at the home of former Colts tight end Jimmie Kennedy.

Narcotics detectives said they arrested Kennedy's brother James and issued a warrant for the former football player, who was not home during the raid.

Officers confiscated 11 ounces of suspected cocaine, 30 pounds of marijuana, three handguns, a shotgun, two rifles and $234 cash. The raid ended a two-month invstigation.

The Colts signed Kennedy as a free agent after he was drafted by the Washington Redskins in 1974. Kennedy was with the Colts from 1975 to 1977.