Nichols is off contract at the end of the season and his agent, Buddy Farah, told The World Game that the 27-year-old wanted to delay committing to a new contract in the A-League, to hold out for a European deal.
"Mitch is 27 and it will probably be his last chance to find a gig abroad where it suits him," Farah said.
"Where's our focus? Europe. Asia could be a focus, but right now it's Europe first and foremost and if that doesn't come around I'm sure we'll be sitting at the desk at some stage at the Wanderers or another club in the A-League.
"He's a big-name player in this competition and I'm sure a number of clubs would be keen on him, but we're not entertaining discussions at the moment.
"Is he happy at the Wanderers? Yes, and 'Popa' (coach Tony Popovic) has been great for him. But Popa was an international player himself, so he knows what players want and how they think in terms of their ambitions.
"Mitch wants to give it a crack overseas if possible and so do I, for him."
Farah also manages Scott Jamieson, the former Wanderers left-back who signed for Swedish club IFK Goteborg last August, two months before his 28th birthday.
Nichols won two A-League championships with Brisbane Roar and also played for Melbourne Victory before embarking on his only previous overseas stint, with Japanese club Cerezo Osaka, in 2014.
But the move didn't work out as he would have liked and he was soon back in the A-League with Perth Glory before switching to the Wanderers on a two-year contract.
Farah said the Popovic effect had been fantastic for Nichols.
"It's the fittest Mitch has ever been and that's credit to 'Popa'," he said.
"Popa has been good for all of the players I manage who have played under him. He takes them to another level with their whole approach. Scotty Jamieson did well under Popa and moved over to Europe after that.
"Mitch hasn't returned the same stats this season as he did last year in terms of goals, but the team is different and he has contributed in many other ways.
"He has created a lot and taken on more of a leadership role this year. He covers a lot of kilometres in the game and does a lot of running off the ball. The results haven't been the best this season, but one player alone can't determine that.
"The bottom line is that the last two years working under Popa has been nothing but a positive for Mitch."