Muhammad Imran converted a penalty corner in the 30th minute to give 1-0 lead to Pakistan.
In the 44th minute, Sohail Abbas scored second goal for Pakistan.
Argentina did get a couple of chances on penalty corner just after the start of the second half but had them saved by Pakistan’s goalkeeper Imran Shah.
Pakistan will play their third Olympic match against Great Britain on Friday at 8pm PST.
Pakistan started their Olympic campaign with a 1-1 draw against Spain—the 2008 Olympic silver medallists—on Monday.