Peyton Manning -- I Loved LeBron's ESPY Speech ... 'Really Effective' (VIDEO)

Peyton Manning tells TMZ Sports he was very impressed with LeBron, Carmelo, D-Wade and CP3 -- saying their passionate ESPYs speech was not only excellent ... but effective.

The NFL legend was leaving LeBron's after-party at Le Jardin in Hollywood when we asked about the powerful opening moment at the award show.

The 4 NBA stars spoke out against gun violence and racial profiling -- and challenged the athletes in the room to get involved in their communities to help solve the problem.

Peyton says he got the message loud and clear.