Vikings star Alexander Mattison says over 60 people sent him disturbing messages following his game Thursday night ... revealing some contained disgusting racial slurs.

The Minnesota tailback said the notes poured into his Instagram message box shortly after he had a down game in the Vikes' 34-28 loss to the Eagles in Philadelphia.

He shared screenshots of two of the DMs on his IG stories -- and, in both, you can read he was called the N-word. The writers also told Mattison he should die by suicide.

The 25-year-old said the words really affected him ... writing in a caption on the screen grabs "this s*** is unacceptable."

"Under my helmet, I am a human," he said. "A father.. A son. This is sick. SMH."

Mattison took over the Vikings' starting running back reins this year following Dalvin Cook's offseason departure ... but through two games so far, he's totaled just 83 combined receiving and rushing yards -- and in Thursday night's defeat, he lost a fumble.

Mattison explained on his social media page that he's OK with people telling him "you suck" over his play on the field ... but he said the latest batch of messages just simply crossed a line.

"SMFH," he wrote. "This is not OK."

Since he shared the screen grabs, several fans have rushed to the comment section on his most recent post to send words of encouragement.

Mattison and the Vikings play next on Sept. 24 against the Chargers.