The Washington Post reporter, who has been jailed in Iran for more than a year, has stood trial on espionage charges.
He is awaiting his verdict, which officials say has been issued but not communicated two months after his fourth and last court hearing.
"We try to resolve the case from a humanitarian point of view," but "the charges are serious and it's a judiciary process," Zarif told reporters, according the official news agency IRNA.
He appeared four times since May at closed-doors hearings before the Tehran Revolutionary Court, a special court that presides over politically charged cases or those related to national security.
Also Read
Gholamhossein Mohseni Ejeie, the judiciary's spokesman and deputy chief, said last week "the verdict for this case has been issued".
"This verdict can be appealed," he said, suggesting Rezaian had been found guilty, but did not detail the judgement.
Washington Post executive editor Martin Baron said the "vague and puzzling" statement from the Iranian judiciary "only adds to the injustice" surrounding Rezaian's case.
The United States has repeatedly called for Rezaian to be freed.