Planeswalkers are not players, so no. The ability specifically says "combat damage to a player".
April 6, 2015 12:23 p.m.
I thought that Planeswalkers are being treated like "players"? So let's say I have a burn spell that only damages creatures, Roast for example. I can't target a Planeswalker with it, right? So when exactly is a Planeswalker a player and when not? Can I target it with Leyline of Lightning?
April 6, 2015 1:57 p.m.
Planeswalkers are never considered to be players. Sometimes you might hear an explanation equating the two, but that's really just a sloppy shortcut and causes more confusion than it's worth (as we can see here).
When you declare attackers, you choose for each attacking creature whether it's attacking an opponent or one of your opponents' planeswalkers. Being able to be attacked by creatures is the only thing players and planeswalkers have in common.
If you would ever deal non-combat damage to an opponent (that is, damage from a spell or ability, not from attacking with a creature), then you can choose to instead deal that damage to one of the opponent's planeswalkers. When someone says "Lightning Strike your Ajani", what they really mean is "Lightning Strike targeting you, and as it resolves I want to deal the damage to your Ajani instead". That takes a long time to say, so people just play using the commonly understood shortcut.