It won 6,015 seats, giving it 21.7 per cent of the national vote, ahead of the governing Istiqlal (Independence) party with 5,292 seats and 19.1 per cent, Chakib Benmoussa said on Saturday.
The local elections were seen as a test for the government of Abbas el-Fassi, the prime minister.
His Istiqlal party's second place finish meant a certain reaffirmation of the government, which had been accused of not having a solid programme despite the Moroccan economy having weathered the global crisis fairly well.
The moderate Islamic Justice and Development Party (PJD), which scored its best result in 2007, picked up only 1,513 seats, putting it in sixth place.
The national turnout was 52.4 per cent, below the 54 per cent recorded in 2003 local elections but well above the 37 per cent figure for legislative polls in 2007.
Morocco's next parliamentary election is due in 2012.