UFC lightweight champion McGregor, who has a licence to box in California, insisted earlier this week he has signed a contract to fight Mayweather and awaits the American's response.
Mayweather had refused to respond in the build-up to Saturday's fight between Gervonta Davis and Liam Walsh but after his fighter's third-round knockout victory sounded increasingly confident of fighting this year.
The 40-year-old has remained inactive since he outpointed Andre Berto in September 2015. Few expected he would retire with a record of 49 victories, level with Rocky Marciano, and in the past 12 months there has been increasing speculation regarding a match-up with Ireland's McGregor.
Asked of his personal plans, Mayweather responded: "If I do fight, there's a 90 per cent chance it's against Conor McGregor
"When I get back to the US I'll call Al (Haymon, Mayweather's advisor) and see our next move. There's no rush.
"The only fight that makes sense to me is the McGregor fight. I guess I have one more obstacle that I have to get over.
"We have to give the people what they want to see. The fans demand that fight; we have to give them what they want to see to make them happy.
"I think this year I'll be back at number one in Forbes' (list of athletes' net worth), in a matter of time."
The 22-year-old Davis had been the recipient of both encouragement and instructions from Mayweather, who was ringside at London's Copper Box Arena to watch his fighter make the first defence of his IBF super-featherweight title.
Mayweather also spoke of the time he had spent in the gym alongside Davis, who though impressive he insists is still "not at 100 per cent".
"It's possible (this fight against McGregor could be made quickly) but we don't want to rush," he said.
"When we make a move it's going to be huge. When Floyd Mayweather fights it's history.
"This kid (Davis) had me go to the gym, sparring a little bit. When it's time to do what I have to I'll look tremendous, and sharp."
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