Captain Morgan and Hales made themselves unavailable for October's trip because of security concerns.
No international side has toured Bangladesh since 20 people were killed in a siege at a cafe in Dhaka in July.
"We're a tight-knit bunch of guys and we will remain that way," wicketkeeper Buttler, 26, told BBC Sport.
"I completely respect the decision that has been made. There are things that happen in the world that are much bigger than cricket.
"Those two guys will have thought long and hard. It's not an easy decision to make.
"I've spoken to Eoin Morgan. He's a friend of mine and very much still the captain of the England ODI side.
"It is a side where a lot of guys have grown up together - there's a lot of close friendships."
