The proposal, part of a new deal with Relevent, the company behind the International Champions Cup, had chosen the January fixture as the first La Liga game to be played in the United States.
Players have voiced their opposition to the plan despite Girona and Barcelona giving the green light to move the match to Miami.
And the RFEF appeared to put the proposal in jeopardy on Friday by writing to La Liga to ask for more details on the agreement.
"What we are being asked now is for more documentation and that is what I will prepare," Tebas said in response.
"I have been with the Delegate Committee all morning and I have not been able to study this letter, which is quite long. We are going to look and prepare everything.
"I am still quite optimistic on all of the issues and we will have to see what happens in the end."
RFEF leader Luis Rubiales has made it clear he opposes the Relevent deal, which he has described as an "invasion" of the United States.
Tebas, though, feels he can convince Rubiales to give the RFEF's blessing to the 15-year deal with Relevent, citing the relocation to Morocco of this season's Supercopa de Espana between Barca and Sevilla.
"He [Rubiales] is not saying no," he added. "But asking for more documentation to be able to resolve any legal issues. Obviously, they do not have much desire, but I am still an optimist.
"There is a precedent of already having played a game in Tangier. We will work on what is asked of us, but I'm surprised that the letter keeps referring to FIFA when [Gianni] Infantino can have his opinion, but it has no place in the regulatory procedure."