Martinez signed him for a reported 4 million pounds in June this year and the 21-year-old has blossomed in England, scoring once and providing six assists in 10 Premier League appearances this campaign.
But Barcelona, who are under a transfer embargo, refused to let Deulofeu leave without a buy-back clause in his contract valid for two years.
"There is nothing we can do if they activate the clause," Martinez was quoted as saying by the British media.
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"That was the deal and the only way we could access the player in the terms that we wanted. I'm delighted with the deal."
According to the agreement, Barcelona cannot re-sign Deulofeu in the January transfer window and, if they decide to activate the clause, cannot sell him on until he has spent at least a season in their first-team squad.
Everton had first right of refusal if the Catalan club decided to sell him and would receive a percentage of any fee if he was sold to another club, Martinez said.
"There are certain things in the deal," the Spaniard said.
"It is 9 million euros for the first year and 12 million euros in the second year. They can't take him back in the winter so they can't take him back in January.
"My worry would be to lose him in January, that would be a big problem.
"But for us to have a player of that quality for the money we paid, if we lose him it will be on a profit financially so we would be able to use the money.
"And you want the player. You're talking about a Barcelona player who has been all through his years as the golden boy believing he is going to be at the top level at Barcelona and we got him for a very good price.
"I'd like to tell Barcelona that he's rubbish but they come to watch our games."
(Reporting by Simon Jennings in Bengaluru; Editing by John O'Brien)
