says he's "focused on resolving personal issues" after being hospitalized for a mental health evaluation this weekend ... but has vowed to return to the field.
As we previously reported ... the Minnesota Vikings star was involved in a bizarre incident at the team hotel on Saturday .. which ended in being.transported to a hospital for a mental health exam.
At the time, team staffers feared he could hurt himself or others.
Griffen spoke out on social media on Thursday ... apologizing for the incident and promising to address his issues.
This past week's events have raised many questions and I want to apologize to everyone who was impacted," Griffen says.