US President Barack Obama says the US is “not as divided as some have suggested” in the wake of fatal shootings involving African-Americans.
Five white police officers were shot dead by a black man, Micah Johnson, during a protest rally on Thursday.
The march was against the killing of black men by police. Two deaths this week have led to nationwide protests.
Mr Obama said “it was just not true” the US was returning “to the situation in the 60s”.
His comments, on the side of a Nato summit in Warsaw, echoed those earlier of Vice-President Joe Biden, who said Americans had a duty to stand up against injustice, but that people also needed to support police.
Johnson, who was himself killed during the assault in Dallas, supported black militant groups who encouraged violence against police.
Dallas police chief David Brown said Johnson had told a negotiator that he had wanted to kill white people, especially white police officers, because he was angry about the recent shootings of black men by police.
The attack came after the police killings of Philando Castile in Minnesota and Alton Sterling in Louisiana.
Mr Obama said Americans of “all races, all backgrounds”, including many of those who were protesting, were outraged by the Dallas killings.
The unity shown in the wake of the attack was a strong foundation on which to build, he said.
“When you start suggesting that, somehow, there is this enormous polarisation and we are back to the situation in the 60s, it’s just not true,” he said.
“You are not seeing riots and you are not seeing police going after people who are protesting peacefully.
“We have seen almost uniformly peaceful protests and we have seen, uniformly, police handling those protests with professionalism.
“And so, as tough, as hard, as depressing as the loss of life this week, we have got a foundation to build on. We just have to have confidence that we can build on those better angels of our nature.”
He also repeated his call for urgent action on gun control, saying anyone who cared “about the safety of our police officers” had a duty to address the issue.
As well as the five police officers killed, another seven were injured. Two civilians were also hurt.
-bbc