According to the original deal, Keita was supposed to become an official Liverpool player in the summer, but after Philippe Coutinho' departure, manager Jurgen Klopp has chose to bring the 22-year-old player already this January.
Keita scored for Leipzig on Saturday as the home side defeated Schalke 3-1 to move to second in the Bundesliga.
Writing on their official Twitter account, Leipzig declared: "Naby Keita will remain an RB Leipzig player until 30th June 2018".
NABY KEITA will not be allowed to move to Liverpool from RB Leipzig this month, the club have announced.
But Leipzig insist Keita will not leave the Bundesliga club until the end of June - the previously agreed date for his transfer.
The Reds will sorely miss Coutinho's creativity and were hoping that Keita could step into his shoes.
Speaking before the game, Rangnick said there had been no contact from Liverpool about changing the existing agreement, reported to worth some €70 million.
Williams' information has however tied in with news that Keita registered a company named "NK8 Limited" - with him as the director and the location in the United Kingdom - earlier this week.