The parents of Martin, 17, were outraged that Zimmerman, a neighbourhood watch volunteer, was allowed to make what they considered a self-serving apology from the witness stand, their lawyer said.
Zimmerman's release from Seminole County Jail could take days as prosecutors and defence lawyers work out agreements on how to protect his privacy. They also must decide whether he will be allowed outside Florida while charged with second-degree murder for killing Martin on February 26 in a case that sparked racial debate across the United States.
"I wanted to say I am sorry for the loss of your son," Zimmerman, 28, told Martin's parents, Tracy Martin and Sybrina Fulton, briefly looking in their direction from the witness stand.
"I did not know how old he was. I thought he was a little bit younger than I am. And I did not know if he was armed or not," said Zimmerman, who was dressed in a suit but still shackled around the waist and wrists.
Trayvon Martin's parents, who divorced in 1999, left the court stone-faced and with arms locked, declining to answer questions from reporters.
Zimmerman's dramatic comments drew sharp criticism from the lawyers for Martin's family, who called it too late to be considered genuine.
"They are devastated" that Zimmerman might soon be free on bail, attorney Benjamin Crump told reporters, adding that Tracy Martin had tears in his eyes throughout the hearing.
"And it was devastating that he got to give a self-serving apology to help him get a bond," Crump said of Zimmerman. "They (the parents) were very outraged at that."
Zimmerman comments could be used by prosecutors later in the case to impeach his credibility should they discover contradictions with previous statements to police.
Assistant State Attorney Bernie de la Rionda was limited in his cross-examination of Zimmerman to the apology and prohibited from delving into the facts of the case. But he made a point of locking Zimmerman into his statement that he also told police he "felt sorry for the family" about the death of Trayvon.
Zimmerman also testified he never changed his story in three separate statements to police.
Moments after the surprise testimony, Circuit Judge Kenneth Lester Jr. set bail of $150,000. Zimmerman's defense lawyer had requested bail of no more than $15,000 and prosecutors, who had opposed his release, suggested bail of $1 million.
Civil rights activists say racial prejudice played a role in the decision by Zimmerman, whose father is white and mother is Peruvian, to view Martin with suspicion as he walked through Zimmerman's gated community. Activists also say race was a consideration by police in not making an immediate arrest.
