A statement on the Guard's website says a probe is underway but that the case is not being treated as an assassination.
Iran's news website Alborz reported this week that a senior Guard official was assassinated west of Tehran. Other reports identified the victim as Mojtaba Ahmadi, a member of the Guard's cyber warfare unit.
The reports brought references to other targeted slayings in recent years, including those Iran blames on Israel.
The Guard says the reason for the death is still unclear. But the headline on its website on Tuesday described the statement as a "denial" of the assassination claims.