WASHINGTON — President Obama on Monday called for prompt action to change police practices across the country after the deaths of unarmed black men in Ferguson, Mo., and Staten Island at the hands of white officers exposed frustrations about law enforcement in minority communities.

Mr. Obama, unveiling the recommendations of a White House task force created in the wake of the killings, said local law enforcement agencies should consider requiring independent criminal investigations and independent prosecutors in cases where the use of force by police officers results in injury or death.

He also said police departments should take additional steps to build trust with communities. They include adopting policies to address racial profiling, relaxing their approach to mass demonstrations and collecting more data on shootings and deaths by the police.

“The moment is now for us to make these changes,” Mr. Obama said at the White House, where he met with members of the task force. “We have a great opportunity, coming out of some great conflict and tragedy, to really transform how we think about community-law-enforcement relations so that everybody feels safer and our law enforcement officers feel, rather than being embattled, feel fully supported. We need to seize that opportunity.”