However, the court on Sunday maintained the charge of "spreading false information on the national security forces", but decreased the penalty of one month imprisonment to two weeks. Salih completed the period of his two-week imprisonment last Friday.
The Sudanese security closed the Aljazeera office in Khartoum last December after raiding it and confiscating broadcasting equipment.
Aljazeera channel, whose motto is "The opinion and the counter opinion", had given government and opposition figures a platform when reporting on Sudan.
Human rights organisations have often condemned Sudan for cracking down on freedom of expression.
In its 2003 report on Sudan, Amnesty International said security forces continued to limit media freedom. Amnesty added that authorities unlawfully arrested journalists and editors and fined or suspended newspapers.