The new owner has placed his faith in present manager Mark Warburton to spark the revival and take the team to the Premier League.
The 49-year-old -- who heads up a consortium with compatriot Socrates Kominakis -- has also been accused in the past of being involved in the bombing of a bakery owned by a referee although no action was taken.
Despite the accusations Marinakis has passed the English Football League's owner's and directors' test bringing the curtain down on the troubled five year tenure of Kuwiati Fawaz Al Hasawi, but UEFA is still monitoring the Greek case and awaiting the outcome.
"All these years, a lot has been said but nothing came out in reality," Marinakis told the BBC.
"All of it has been dismissed and we have been clear from all of this.
"Now there is a last case remaining - there are about 80 persons involved.
"I can tell you again that I have nothing to do with it because I know very well what I have done and how I have achieved victories.
"Of course I cannot stop our opponents talking or bad-mouthing."
Marinakis, under whose aegis Olympiakos have won seven league titles since he became owner in 2010, says Forest deserve to be in the Premier League but accepts that it may take time -- they only avoided relegation to the third tier League One on the last day of the season.
"We have a long-term plan and within this long-term plan we want to bring Nottingham to where it belongs," said Marinakis, who was educated in England from the age of 15.
"And of course Nottingham belongs in the Premier League. And Nottingham belongs to the elite of the Premier League.
"Furthermore the supporters of Nottingham have been tired all these years, they didn't have such good times.
"But they remained loyal and for us that's very important.
"The potential is huge.
"The potential of this team is that when it will be very well organised, when it will achieve victories again, when it will have a better position in the Championship, when it will have a better position and we can look seriously at the Premier League, then we will be there to stay."
Marinakis has also placed his faith in present manager Mark Warburton who will endeavour to spark the revival and begin the process of a return to the Premier League which they have not played in since being relegated in 1999.