West Ham went in front twice on the night with goals from Vaz Te and Mohamed Diame.
United's first equaliser came from Antonio Valencia and with 17 minutes left on the clock Van Persie came up with something of a controversial equaliser
The Dutchman reacted quickest to the loose ball after Shinji Kagawa's effort hit the post, and though he appeared offside, but the assistant referee failed to raise a flag and the goal stood.
Four more points will win the Reds the title back unless City lose at Tottenham on Saturday then the title could be sealed with a win over Villa at Old Trafford on Monday.
“We had to stand up to a lot, we went down twice but we kept going. We played like champions tonight,” the boss said.
“We’re determined to win; we don’t like losing and showed that again.”