Alfie Barker of Hitchin Town, a seventh-division side, had his contract terminated after abusing Harry Arter over the death of the Bournemouth midfielder's baby daughter.
Barker tweeted: "Big hype just for a disappointment like the nine months leading up to your child's birth."
Barker said that he was hacked before he apologized and called his comments “disgraceful.”
"I'm sorry for every comment made,” Barker wrote. “I'd like to apologize to Harry Arter and his family for such disgraceful comments and I'm sorry from the bottom of my heart.”
Arter's stillborn daughter Renee died in December 2015.
Codicote FC, where Barker is on loan, has also terminated its contract with the player. The Football Association is also investigating the matter and how it applies to its social media guidelines.
Speaking to the BBC, Hitchin manager Mark Burke said, "I've seen the tweets and I'm disgusted with them. They're vile and I can't condone them in any way."