Rachel Nichols is proud of NBA stars like Carmelo Anthony for using their voice to try and make the country better. (1:55)

In the wake of the tragic shooting in Dallas that left five law enforcement officers dead, New York Knicks forward Carmelo Anthony took to social media Friday morning to ask athletes to "step up" and "demand change" without resorting to violence.

"Shooting 11 cops and killing 5 WILL NOT work," Anthony wrote on Instagram. "... I'm calling for all my fellow ATHLETES to step up and take charge. Go to your local officials, leaders, congressman, assemblymen/assemblywoman and demand change. There's NO more sitting back and being afraid of tackling and addressing political issues anymore. Those days are long gone. We have to step up and take charge.

"We can't worry about what endorsements we gonna lose or whose going to look at us crazy. I need your voices to be heard. We can demand change. We just have to be willing to. THE TIME IS NOW. IM all in. Take Charge. Take Action. DEMAND CHANGE."

LeBron James, who said Anthony's Instagram post was "on point," also reached out on Twitter to implore people to stop the violence.

We are all hurting tonight. More violence is not the answer. #StoptheViolence — LeBron James (@KingJames) July 8, 2016

In addition to the five officers who died, seven officers and two civilians were also injured Thursday night after an ambush in downtown Dallas following a peaceful march to protest the fatal shootings by police officers of two black men -- Alton Sterling in Louisiana and Philando Castile in Minnesota -- this week.

"Obviously, violence is not the answer of solving it," Serena Williams said Saturday after winning her seventh Wimbledon title in London. "The shooting in Dallas was very sad. No one deserves to lose their life, doesn't matter what color they are, where they're from.

"We're all human. We have to learn that we have to love one another. It's going to take a lot of education and a lot of work, I think, to get to that point. But I think, in general, the entire situation is extremely sad, especially for someone like me. It's something that is very painful to see happening."

Former Dallas Cowboys receiver and Pro Football Hall of Famer Michael Irvin, speaking to The Dallas Morning News at his football camp, said: "You can let it beat you, or you can rally together and say, 'Not on my watch.'

"And that's what the community in Dallas I'm sure will say, 'Not on my watch,' " Irvin said. "We will not allow this on our watch. We will rally together.'"

Irvin said football could help bridge the divide that permeates much of the nation.

"It gets rid of some of the issues we are dealing with," Irvin said. "With what happened here in Dallas and Minnesota and Louisiana. The game of football helps move past those things."

Texas Rangers outfielder Nomar Mazara reacted Friday to a photo posted on Instagram by teammate Joey Gallo that was taken a month ago with Dallas Police Department officer Patrick Zamarripa, who was identified as one of the officers who was killed Thursday night.

"Who would expect that you would take a picture with somebody a month ago and they'd be dead today," Mazara said. "He was a nice guy. He recognized us and we took a picture and talked baseball for about 15 minutes."

Dallas athletes also expressed their emotions on social media following Thursday night's attack.

It is the #Lives that are lost that we are not honoring if we keep having this divide #Fam! This idea is not only about tonight #PEACE !!! — Marcus Spears (@mspear96) July 8, 2016

Our community is stunned this morning. My thoughts and prayers go out to the fallen police officers and their loved ones. — Tony Romo (@tonyromo) July 8, 2016

Black lives Matter,White lives matter,Hispanic lives matter,Latin lives matter,Asian lives matter,All lives matter,Yo life matters! #Truth — Deion Sanders (@DeionSanders) July 8, 2016

Dallas,we mourn those who lost their lives protecting us and stand together, united, to cherish those we live and work next to #DallasStrong — Mark Cuban (@mcuban) July 8, 2016

Still in shock. Saddened to hear about the tragic events in Dallas. My Thoughts are with everyone, who are affected. #StoptheViolence — Dirk Nowitzki (@swish41) July 8, 2016

Man what is going on right now. I don't wanna live in fear! I want to be free and walk around my city. Not scared of my every move! — Justin Anderson (@JusAnderson1) July 8, 2016

"We need to steer our anger in the right direction," Anthony wrote. "The system is Broken. Point blank period. It has been this way forever. Martin Luther King marched. Malcolm X rebelled. Muhammad Ali literally fought for US. Our anger should be towards the system. If the system doesn't change we will continue to turn on the TVs and see the same thing. We have to put the pressure on the people in charge in order to get this thing we call JUSTICE right."

ESPN Staff Writer Jean-Jacques Taylor contributed to this report.