According to Navy spokesman Joe Carpenter, Kettani, 21, must serve a minimum five-year service obligation as a surface warfare officer before he can pursue a pro football career.
The decision was made by Vice Adm. Jeff Fowler, Navy's superintendent.
"A number of factors were considered," Carpenter said. "He was denied participation because it wouldn't be consistent with current Navy efforts to support active-duty readiness during wartime. His participation could incorrectly imply that the Navy would support in him pursuing a professional football career immediately after graduation."
Gil Brandt, a former NFL personnel director who works at the combine for NFL.com, called Kettani a legitimate prospect.
"It wasn't a political invitation," Brandt said. "The guy ran under 4.6 [seconds in the 40-yard dash] at his pro day [last year], and he weighed 243 pounds. He had a good vertical [jump], and he's really a good athlete. This kid's the real deal."
Because of his service obligation, it's unlikely Kettani would be drafted in April. Army's Caleb Campbell participated in the combine last year and, with considerable fanfare, was drafted in the seventh round by the Detroit Lions. But the Army changed its policy in July and Campbell was required to fulfill his active-duty obligation.
Under a Department of Defense policy, an academy graduate with unique abilities can serve two years of active duty and then six in the reserves. But Donald C. Winter, secretary of the Navy, suspended the policy because of the wars in Iraq and Afghanistan.
"We respect the decision of the U.S. Navy," said Chad Wiestling, Kettani's agent. "I know Eric is very disappointed in the decision. What the combine basically is, it's a job interview. My take on it is that the Navy is denying him an opportunity to interview for a post-military career, whether right or wrong."
Kettani, who rushed for 1,862 yards and 14 touchdowns in the triple-option offense the past two seasons for the Midshipmen, was traveling yesterday and unavailable to comment.
A native of Kirtland, Ohio, Kettani is 6 feet 1 and 243 pounds. He was also invited last month to the Senior Bowl, an all-star game in Mobile, Ala., for the nation's top prospects, and received permission from the academy to participate. He carried only once but scored on a 1-yard run.
"It was an NCAA event and consistent with his participation in college sports," Carpenter said. "The issue here is not college sports; it's service obligation upon graduation."