[khRamin78]

there is no function like that but you can do something like this!
in a timer or onplayerupdate! idk
Check if the player is using Any Key > UP-DOWN-LEFT-RIGHT
and the player is on the foot(not in the vehicle)
and do this

Code:

ApplyAnimation(playerid,"PED","WALK_player",4.1,1,1,1,1,1);

and whenever it is a player Holding space key!
just don't call that apply animation ! so it will be samp default run!