Barca may need to meet Williams' €58m buyout clause in his contract to prise him from Athletic Bilbao.
And Tebas says, after two years of Barca battling a cash crisis, they're now in a position to buy players within the LaLiga's spending cap.
He told Sport: “If you get to the 1:1 norm, you can do it. You have to think that with Barcelona's effort to reduce its wage bill and levers by more than 200 million, it can perfectly incorporate a player like Nico Williams.
"I think he has a termination clause of 58 million: when you buy for 58 million, the amortization is divided by the years of the contract; If you sign three, it would be less than 20 million per year, plus what you pay the player. Barça will be able to be in those quantities, perfectly acceptable if it is in the 1:1 norm.
"It is a club that is close to 1,000 million in turnover, it can be along that line.”