The 22-year-old is thought to be unhappy in Rome after being left out of the Lazio side that beat Lazio 3-2 in the Italian Super Cup.
Following his Super Cup snub, the winger tweeted: “The lack of a call-up for the Super Cup Final has profoundly hurt me.
“It is the first important match of the season, for which I had prepared and was ready for action.
“The decision made by the club, which evidently had nothing to do with purely sporting criteria, puts me in a psychologically uncomfortable position and right now I don’t know how to evaluate the consequences of that.”
The Senegalese international has just 12 months left on his contract and Tottenham are hoping to take advantage of that to seal a cut-price deal.
Keita, who spent seven years at Barca's famed La Masia academy as a youngster, scored 16 goals in 34 Serie A games last season with eight coming in his last five games of the season.
Spurs boss Mauricio Pochettino is believed to have given the player priority status as he tries to strengthen his squad before the end of the transfer window.
However, the Argentine will have to see off competition from Serie A champions Juventus, who are also keeping a close eye on the player.
In fact following the Super Cup Juventus' club president Giuseppe Marotta admitted he had spoken Lazio counterpart Claudio Lotito about a potential move.
“There was a meeting with president Lotito and the proposal of a sum that was considered inappropriate by him," he said.
“We will see if there will be a chance later, I do not know.