Khairkhah worked for the Afghan National TV channel and hosted several social programs. He was shot near the police checkpoint in Khost and died in hospital from his injuries.
The Taliban denied responsibility for the journalists killing.
AIJA vice president Hujatullah Mujadidi condemned the incident and urged the Afghan security community to arrest the prepetrators.
Anthony Bellanger, general secretary of the IFJ said: "We condemn the murder of Sultan Mohammad Khairkhah. The Afghan authorities must take immediate action to investigate the murder and bring those responsible to justice. Journalists must be safe to continue their work."
According to IFJ statistics, Afghanistan was the deadliest country for journalists in 2018, with 16 journalists and media workers killed. Khairkhah is the third journalist killed in Afghanistan this year.