The French forward was subbed off for Omar Salgado in the 84th minute of the MLS clash but walked straight down the tunnel at JELD-WEN Field and did not join his teammates on the bench.
Hassli admits that he was experiencing plenty of frustration and said that this was the reason for him storming off the pitch.
"A lot of frustration," Hassli said through a translator, when explaining his petulant behavior. "I regret doing that now but you have to look forward, not backwards.
"I was frustrated to lose the match and also to lose so many matches.
"I don't want to give the wrong impression to the other players," he added. "I have a lot of respect for them and I don't want them to look at me in the wrong light that way."