Jennifer Lopez was reportedly paid $1.5 million to perform for the Turkmenistan leader.
The singer sang Happy Birthday Mr President to Gurbanguly Berdimuhamedow at a controversial concert in the Central Asian state.
The country has been described as having "one of the world's most repressive" regimes because of its terrible human rights record.
Jennifer's performance took place in the $2 billion resort of Avaza, a huge luxury complex on the country's Caspian coast.
"Her private, one-off fee rate is $1.5 million non-negotiable, plus private jet and hotel for her and her entourage," a source told Radar Online. "Once expenses are included, this gig could have run closer to $2 million."
Jennifer's publicist went into damage control after her performance, declining to name the star's price tag and issuing a carefully worded statement.
"Had there been knowledge of human rights issues of any kind, Jennifer would not have attended," the representative said.
Jennifer was hired by the China National Petroleum Corporation for the event, reportedly held to celebrate Mr.Berdimuhamedow's 56th birthday.
The statement added that Jennifer "graciously obliged" a last minute request to sing Happy Birthday to the dictator at the end of her performance.
Jennifer's manager has also weighed in on the row, telling TMZ that the star believed she was in Turkmenistan to perform a corporate concert and did not know the Mr.Berdimuhamedow was in the audience.
Benny Medina said there have been no discussions about Jennifer returning her fee.
Meanwhile, human rights activists have spoken out against her decision to perform.
"Lopez obviously has the right to earn a living performing for the dictator of her choice and his circle of cronies," Human Rights Watch president Thor Halvorssen told Radar in a statement.