MIAMI — A 5-year-old Cuban girl at the center of an international custody dispute should be returned to her father, unless separating the child from her Miami foster parents would cause her extreme harm, a judge ruled yesterday.

Circuit Judge Jeri Cohen said she would not immediately return the girl to her father, farmer Rafael Izquierdo, who wants to take her back to Cuba. But she said he is a fit father and that the state would have a difficult time proving a reunion would harm her.

The Florida Department of Children & Families wants the girl to stay with the foster parents. Judge Cohen said she would hold a follow-up hearing to listen to the state’s arguments but urged agency attorneys to “take their blindfold off and see the forest for the trees.”

“I have read the cases in Florida, and you’re going to have a very steep mountain to climb here, and you know it,” she told attorneys for the state. She suggested all parties enter into mediation.

The girl went into foster care after her mother brought her to America in 2005 and then attempted suicide days before Christmas. For the past 18 months, the girl has been living with foster parents Joe and Maria Cubas, a wealthy Cuban-American couple. State attorneys said Mr. Izquierdo abandoned the girl by not keeping in contact with her. Mr. Izquierdo denied that and professed his love for her.

Judge Cohen ruled that Mr. Izquierdo neither abandoned nor neglected his daughter, even though he went months without communicating with her after she moved to America.

The state’s attorneys have said removing the girl from her foster home after such a long time would cause her serious emotional trauma. The department maintains the girl has bonded with the Cubases and wants to remain with her half brother, whom the couple adopted.

Judge Cohen said the court couldn’t deny Mr. Izquierdo custody of his child unless it would endanger her. At a news conference held outside the courthouse, Mr. Izquierdo, a pig and potato farmer, said in Spanish: “Truth wins.”

Mr. Izquierdo said the Cubases knew all along that the girl had a loving father who wanted her back and that he wants to return home as soon as possible to the central Cuban town of Cabaiguan.

“I want to be with my family, be together,” he said.

His lawyer Ira Kurzban said he was unaware of any cases in Florida where a father, after being found to be fit, was denied custody based on “nebulous” psychological harm a child might suffer from being separated from foster parents.

“Unless a father is unfit, he has a right to his child. Period,” Mr. Kurzban said.

DCF spokeswoman Flora Beal said afterward, however, that “to separate siblings from each other does have an emotional and psychological effect.”

The father, foster parents, and mother were all in court as the judge read her 47-page ruling over several hours. Mr. Izquierdo’s efforts to regain his daughter once she was put in foster care “were not marginal for a man of his circumstances,” Judge Cohen said.