In a video published by The Players' Tribune on Saturday, Sherman said "we should be more focused on uniting our country and showing one another how similar we are."
Sherman also said he found it "very interesting" that Trump chose to condemn protests against bigotry, racism and hatred.
On Friday, Trump appeared at a rally in Alabama and said he would like to see an NFL owner release a player who has kneeled in protest during the anthem because it "disrespects the flag."
"Wouldn't you love to see one of these NFL owners, when somebody disrespects our flag, to say, 'Get that son of a bitch off the field right now, out, he's fired. He's fired,'" Trump said, per CNN's Brian Stelter. "You know, some owner is going to do that. He's going to say, 'That guy that disrespects our flag, he's fired.' And that owner, they don't know it [but] they'll be the most popular person in this country."
Sherman, who is a member of the NFL Players Association Executive Committee, tweeted Saturday that Trump's behavior was "unacceptable."
Sherman's teammate, wide receiver Doug Baldwin, also penned a note (via The Nation's Dave Zirin) and said he believes Trump's comments can be "a unifying moment for sports."
After NFL Commissioner Roger Goodell issued a statement Saturday morning saying "divisive comments" like Trump's "demonstrate an unfortunate lack of respect for the NFL, our great game and all of our players," Seahawks president Peter McLoughlin echoed those remarks.
"We fully support players' use of their freedom of speech and peaceful action to highlight the existing racial and other divides in our country," he wrote. "Our players completely respect the military and veterans of our country; however, they believe these issues need to come to the forefront."