"While they go ahead with this destruction and this macro-project by decree and without public debate, the people cited and their properties will be an Eta target."
Eta said that the construction of the high-speed rail link between the Basque cities of Vitoria, San Sebastian and Bilbao to the Spanish capital was not in the interests of Basque people.
In Wednesday's statement, the group also said it carried out two bombings in November and December, one outside a regional television station and the other at a telephone mast.
It also said there would be more attacks against the media.
Eta, which stands for Basque Homeland and Freedom, in the Basque language, has killed more than 825 people since 1968 as part of its campaign for an independent homeland.