The BBC reports that President Jammeh sent an official notice to Ambassador Momodou Njie in Dakar, Senegal, notifying him about the decision.
At least five Gambian diplomats have called upon Jammeh to step down following his defeat in the December 1 poll.
Jammeh initially conceded defeat and even called president-elect Adama Barrow on live television to congratulate him for winning the election.
He however receded this decision, saying the election was marred by irregularities.
He has vowed not to step down, and instead wants a new vote conducted.
ECOWAS leaders have asked the president to step down and let Barrow take over power. They have even come up with a stand-by force that they say will be deployed in Gambia should Jammeh refuse to hand over power to the president-elect.