A sanction was a type of action taken by one government against another, usually as a pressure tool or punishment. The term could also refer to actions taken by governments or organizations against their own, to punish illegal actions.
During the negations for the Coalition of Planets, in 2155, Tellarites pushed for trade sanctions against the Orions, which they claimed were pirating Tellarite freighters. A Coridanite ambassador expressed his people's opposition to these sanctions. (ENT: "Demons")
In 2366, on Ansata terrorists took hostage Starfleet personnel and subsequently demanded that the Federation levied an embargo and trade sanctions against Rutia IV. (TNG: "The High Ground")
In 2372, amid calls to reintroduce the D'jarra system on Bajor, Vedek Porta suggested sanctions, among them deportation, for those refusing to submit to the system. (DS9: "Accession")
By 2375, the Federation had ordered sanctions against the Son'a for more than one reason. As a result of sanctions, it was believed that they had stopped raiding planets for slaves. (Star Trek: Insurrection)