Citing three sources familiar with the matter, Reuters said that the court issued the ruling on Wednesday.
"The action for the reversal of the ruling was accepted by the court," the source told Reuters. "It will be hard to overrule that (the appeal court's ruling)."
It was not immediately clear if the US or Greek governments would challenge the ruling, which was given in the appeals court of the region of Chalkis, the agency said, adding that the result of the appeal has not yet been made public.
In April, Greece impounded the Iranian-flagged Lana, formerly Pegas, with 19 Russian crew members on board in Greek waters due to EU sanctions.
The ship was soon released. But in May, Greece issued a court ruling allowing the US to confiscate part of the Iranian oil cargo held onboard and transferred it to another vessel.
Iran strongly protested the move and called it international piracy.
Iran said that Greece had issued the initial court ruling under US pressure.
Several days after the incident, Iran seized two Greek ships in the Persian Gulf over “maritime violations.”
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