The two were detained during a pre-dawn raid and were of Spanish nationality but with Moroccan origins.
A statement released by the Interior Ministry said the arrests were part of an ongoing anti-terrorist operation that saw four members of the same jihadist cell arrested in January.
Those held on Tuesday morning “formed part of a terrorist cell that was fully prepared and ready to attack on national territory,” said the statement.
Mohamed Al Lal, and his brother Farid and another pair of brothers, Anuar and Radouan Alli Amzar, are thought to have been part of a terrorist cell, which was planning attacks in Spain.
In those January raids, police seized an automatic pistol, machetes and military uniforms. The government said those four suspects were highly trained and disposed to launch attacks in Spain.
Tuesday's statement said the two latest suspects were thought to be members of the same cell as the other four.
A coastal city fenced off from northern Morocco, Ceuta has one of Europe's only two land borders with Africa, along with another Spanish territory, Melilla, to the east.