"I hope that the situation in Lebanon remains calm and the channels of dialogue between the different political groups open," EU External Relations Commissioner Benita Ferrero-Waldner said in a statement.
She encouraged political continuity among the various parties following the resignation of the entire government.
Karami himself resigned on Monday in the face of mass protests taking place in Lebanon, bringing to a head a political crisis sparked by the murder two weeks ago of his predecessor Rafiq al-Hariri.
The announcement was greeted with loud applause in the national assembly in Beirut, where the opposition had been seeking a vote of no confidence in Karami's four-month-old government.
"In this difficult period Lebanon is facing after the tragic events of 14 February, it is important for parliamentary elections to take place as planned in May," Ferrero-Waldner said.
"These forthcoming elections should be held in accordance with a free and fair electoral process, without any foreign interference or influence, and under the sovereign control of the Lebanese authorities," she said.