[Konstantinos]

Use it on command.

pawn Код:

if( DM[ playerid ] == true ) return SendClientMessage( playerid, -1, "You cannot spawn a vehicle during DM!" );
// code for spawning vehicle

Or just

pawn Код:

public OnPlayerStateChange( playerid, newstate, oldstate )
{
    if( oldstate == PLAYER_STATE_ONFOOT && newstate == PLAYER_STATE_DRIVER )
    {
        if( DM[ playerid ] == true ) DestroyVehicle( GetPlayerVehicleID(playerid) );
    }
    return 1;
}