The threat level announcement was made at a meeting of government representatives, the country's ruling People's Party and the main opposition force Spanish Socialist Workers' Party.
The minister stated that, according to preliminary information, there were no Spanish citizens among the victims of the gun attack on Friday in Tunis.
In the Sawaber district of Kuwait City, earlier in the day, a suicide bomber detonated an explosive during Friday prayers at a Shiite mosque, killing at least 25 people, according to local interior ministry.
Another attack on Friday occurred at a US-owned gas factory near France's second-largest city of Lyon, leaving one dead and two injured.
In a third incident on Friday, unidentified gunmen opened fire on a hotel near the Tunisian resort town of Sousse. At least 37 people have been killed in the attack, Al Mayadeen television reported, citing the country's health ministry.