The Daily Mail says the pair had to be separated as both teams headed to the changing rooms.
The Frenchman was left in a rage after a heavy first half tackle by Cresswell, which earned the Hammers left-back a booking, which left Knockaert needing treatment.
The Seagulls star headed straight for the England international at half time.
When asked about Cresswell's tackle on Knockaert, Brighton manager Chris Hughton said: "I've seen [it]. I think it was a bad challenge."
The Seagulls beat the Hammers 3-1 to move to 13th in the table and three points off the drop zone.