Pittsburgh Steelers defensive end Cam Heyward is apologizing after socking Justin Herbert in the stomach during Sunday Night Football ... saying "there was nothing malicious behind it."
The controversial play went down with just over 9 minutes left in the 4th quarter of the wild matchup ... when 32-year-old Heyward chased Herbert down and tackled him after a 36-yard scramble.
After the play, Heyward remained on top of Herbert for several seconds ... before Chargers WR Joshua Palmer rushes up to push him off.