A by-election was held in Seshego, part of the Polokwane voting district, on Wednesday.
"Firstly, Mr Malema was allowed to approach the voting station in his convoy, and was allowed to drive into the IEC's cordoned-off area that surrounded the voting station," spokesperson Mmusi Maimane said on Thursday.
Voters are usually only allowed to enter this area on foot to wait in line to vote.
Malema was also allowed to skip the queue and go straight to the voting booths.
In every other election, the DA and the ANC's leaders had always waited [for] their turn in line, the DA said, adding the IEC should treat all South Africans equally.
"Mr Malema yesterday [Wednesday] showed his disrespect for other voters by jumping the queue," Maimane said.
The IEC barred other voters from entering the voting hall while Malema was casting his ballot.
"DA representatives inside the voting hall report that the IEC issued a specific instruction to keep other voters out of the hall while Mr Malema was voting," he said.
"Special arrangements were made for one individual, whilst other voters had to wait in line outside."
The party said this was unacceptable, adding it wrote to the IEC for an explanation of the matter.
IEC spokesperson Kate Bapela was not immediately available for comment. – Sapa