Jammeh initially conceded defeat on state television after 22 years in power, but a week later reversed his position, denouncing the election results and demanding a new vote.
Last week, Gambian troops took over the Independent Electoral Commission office in the capital, Banjul, and instructed its chairman to leave while barring other employees from entering.
Jammeh’s pledge to stay was broadcast on state television on Tuesday and indicated a hardening of the veteran president’s position. It came a day after president-elect Adama Barrow said he was ready to take office on January 18 – the day Jammeh’s mandate ends.
“I am not a coward. My right cannot be intimidated and violated. This is my position. Nobody can deprive me of that victory except the Almighty Allah,” Jammeh said.
He also condemned West Africa’s regional bloc ECOWAS for what he termed “meddling” in The Gambia’s affairs.
The political crisis in The Gambia will be settled internally and peacefully, Jammeh said, adding he would maintain his position of challenging the election result.
A spokesman for the opposition coalition that backed president-elect Barrow assured on Tuesday that Jammeh will not face prosecution on leaving office.
Jammeh’s government has been accused of detaining, torturing and killing opponents.
“ECOWAS wanted to know whether the incoming administration plans to prosecute outgoing President Yahya Jammeh,” spokesman Halifa Sallah said after talks with the Economic Community of West African States on the peaceful transfer of power.
“There is no indication of a threat [of prosecution] or the need to threaten outgoing President Yahya Jammeh,” he said.
“President-elect Barrow says he is going to treat outgoing President Yahya Jammeh like a former head of state and would consult him for advice,” Sallah told AFP news agency.
Backing the opposition candidate, French President Francois Hollande said the results of the December 1 polls were “indisputable”, and Barrow “must be installed as soon as possible”.
Last week, ECOWAS said Jammeh must step down when his term runs out and vowed “to take all necessary action to enforce the results” of the poll – without spelling out what those measures might be.
Jammeh, who came to power in 1994 as a 29-year-old army officer following a military coup, had won four previous polls.