TEHRAN, Young Journalists Club (YJC) - Turkish state television TRT reported that the court in the southwestern city of Mugla issued the ruling on Wednesday. The trial began on February 20.
The defendants have been accused of killing two policemen during an attack on a luxury hotel in the Aegean resort of Marmaris, where Erdogan was on holiday with his family.
The Turkish president reportedly fled the hotel shortly before it was stormed and flew back to Istanbul.
Former Brigadier General Gokhan Sahin Sonmezates was among the defendants and was accused of directing the plot.
The trial is one of many such processes taking place across Turkey to try those who were allegedly involved in the failed coup in July last year.
Some verdicts have already been given in lower-profile cases but it is the first ruling involving top plotters.
Turkey witnessed a coup attempt on July 15, 2016, when a faction of the Turkish military declared that the government of President Erdogan was no more in charge of the country. However, over the course of two days, the putsch was suppressed. Almost 250 people were killed and nearly 2,200 others wounded.
The Turkish government accuses the US-based cleric Fethullah Gulen of having orchestrated the attempted coup. Gulen, a former Erdogan ally turned arch-foe, has denied the allegation.