The charge stems from a May 27 incident in which Merling's pregnant girlfriend claimed in a 911 call that the defensive end hit her "about five times" in the face, The Palm Beach Post reported.
The state attorney's office told The Post that Merling had pleaded not guilty and his attorney asked for a trial by jury. A court date hasn't been scheduled, but that likely will happen within a week, according to the newspaper.
If convicted, Merling could face up to 15 years in prison and a fine of up to $10,000.
A telephone message left with Merling's attorney wasn't immediately returned to The Associated Press.
Merling practiced with the Dolphins in May, less than 24 hours after being freed from jail on $15,000 bond. Merling was the fourth Dolphins player to be arrested this offseason -- a fact that coach Tony Sparano called "frustrating."
Sparano also said the NFL was investigating the incident and that the Dolphins were helping the league gather facts. Merling could be punished for violating the NFL's personal-conduct policy.
Merling, a second-round draft pick by the Dolphins in 2008, hasn't lived up to expectations, recording just 3.5 sacks in two seasons. If the Dolphins decided to cut Merling, they would save $1.3 million in salary, The Post reported.
The Dolphins are scheduled to open training camp July 30.
The Associated Press contributed to this report.