The two sides faced off during a 2½-hour hearing Friday before Nelson at the Seminole County courthouse in Sanford, Fla.
The Miami Herald, the Orlando Sentinel and other media companies fought back against the gag order, saying the prosecutor did not present enough evidence to prove it was necessary.
"Judge Nelson recognized that gag orders can be used only as a last resort if there is no other way to make sure there will be an impartial jury," said Scott Ponce, an attorney for The Miami Herald and other media companies. "Judges have a lot of tools they can use to make sure jurors are impartial, and Judge Nelson is going to use those tools instead entering of a gag order."
The judge added that she ruled on the order "without prejudice," meaning the lawyers can file more motions on the issue in the future. It was the second time de la Rionda asked for a gag order.
O'Mara is an Orlando criminal defense lawyer who launched a novel public relations strategy, which included a website dedicated just to that case and a Twitter account. A Facebook page was abandoned when it quickly devolved into bickering among users. He has held occasional news conferences and given both national and local TV and newspaper interviews.
O'Mara said he turned to social media to turn around an onslaught of negative publicity that preceded Zimmerman's arrest. An employee does the bulk of his social media and website announcements.
Trayvon Martin, 17, was in Sanford on Feb. 26 serving out a suspension from Michael Krop Senior High School, where he was a junior. Martin encountered Zimmerman on the way back from a convenience store; the neighborhood watch volunteer did not recognize the teen and found his behavior suspicious.
They struggled, and Zimmerman says he was forced to shoot an unarmed attacker in self-defense.
In a separate ruling, Nelson said prosecutors will not have access to Zimmerman's medical records from before the February shooting.
A trial is tentatively set for June 10.