Well, there are lasers.

https://en.wikipedia.org/wiki/HELIOS

The High Energy Laser with Integrated Optical-dazzler and Surveillance (HELIOS) or Mk 5 Mod 0 HELIOS[1] is a Lockheed Martin-developed 60 kilowatt high-energy laser weapon designed to intercept combat drones, fast-attack craft, and missiles.[2] After winning the contract in 2018, the first announced installation was on USS Preble (DDG-88) in 2019.[3] By 2021, it was reportedly deployed onto the Arleigh Burke-class ship as part of its anti-air Aegis Combat System.[2][4]

Soundwaves can be powerful enough to deafen, disorient, knock over, or even kill.

Directing sound potent enough to do this from more than a few few, tho, is kinda hard but they have seen use as anti-riot devices.

https://en.wikipedia.org/wiki/Long-range_acoustic_device

https://en.wikipedia.org/wiki/Sonic_weapon

Thing is, anything that will knock a human down will also do much more. There is no nice setting between "lethal" and "non lethal" weapons. A strong push of air will knock somebody down. And rupture their eardrums, and maybe break a rib puncturing their lungs and kill them. Or just explode an eyeball if the blasts hits the wrong way. Or they just suffocate because the shock collapses their lungs.

We can easily knock people down. The problem is, they usually never get up afterwards.

Anything harder than air will turn you into a sludge on the pavement. Even water will rip your skin off and break bones.