Mathews became the first player in the 146-year history of international cricket to suffer the dismissal when he exceeded the two-minute limit to take strike when he arrived at the crease to bat.
The 36-year-old pleaded that the strap on his helmet wasn't secure and, as a result, wasn't ready to face his first ball.
"One of our fielders came to me and said that if I appealed, he would be out," said Shakib who was voted man of the match in his team's three-wicket win.
"The umpire asked me if I was serious and whether I would take it back or not. I said no. It's in the laws; I don't know if it's right or wrong. I felt like I was at war.
"Whatever I had to do, I did it. There will be debates. Today that the timed out helped, I won't deny that."
Sri Lanka captain Kusal Mendis said that a little common sense should have been applied.
"When Mathews came to the crease, there were five seconds left," said Mendis.
"When he came out, he found out about the strap on the helmet.
"It's disappointing that the umpires couldn't step in and make good decisions."
