The incident happened near the end of Los Angeles' 33-30 victory.
Photos published by the Pittsburgh Current and video presented to KDKA-TV showed two men, one wearing a suit featuring the Chargers' logo and the other dressed in black, arguing. A woman dressed in a Chargers jersey attempted to intervene. The man in black briefly grabbed the woman by the throat before letting go.
The Pittsburgh Current identified the male Chargers fan as Daniel Minshew. Minshew said the woman involved was his wife. Minshew told the Current he planned to contact the authorities to file charges against the other man.
A Heinz Field spokesman said in a statement that information about the altercation will be turned over to police.