Goalie Jonathan Quick stopped all 23 shots he faced to record his 49th career NHL shutout and fifth of the season.
"It's hard to win games when you can't score," said Flames defenceman Dougie Hamilton. "They had three powerplay goals. We didn't give up too much, I thought, five-on-five. They're good players over there. You can't give them too many opportunities to do that and they made good plays on the goals, so it's tough."
Already missing forwards Sean Monahan and Matthew Tkachuk due to injuries, the Flames also played without Johnny Gaudreau. Calgary's leading scorer returned home to New Jersey to be with his father, Guy Gaudreau, who suffered a cardiac event on Sunday.
"Johnny alone is probably half of our chances or close to (half)," said Calgary coach Glen Gulutzan. "You take Chucky and Mony out, that's a big whack of goals and chances, so it's harder to create. We came into this game thinking that if we can limit how many chances that we give them, which we did, but we leaked too much on the penalty kill."
The Flames will now look to rebound at home against the Columbus Blue Jackets on Thursday.
"I've been in this situation before," Smith said. "It's about playing to the end. You're paid real good money to be in this league. I think even when you're not in a playoff spot, you don't take it for granted.
"It's not a fun time of year when you're not in the playoffs and this year's no different, obviously probably even more disappointing considering where we were at the halfway point and how everything unravelled."
Early in the first period against the Kings, Mark Jankowski turned and fired a shot on net, but Quick stood his ground to make the save.
At the other end of the ice, Smith stopped a point-blank shot fired his way by Carter before making a pad save to turn aside a scoring chance from the slot by Kopitar.
The Kings took a 1-0 lead during a powerplay at 4:04 of the second stanza when Phaneuf's point shot found its way into the back of the net behind Smith, who was screened by Tyler Toffoli.
Kopitar than snapped a shot into the net at 11:55 during a man advantage for the Kings to put the homeside up by a pair of goals.
LA went up 3-0 at 8:24 of the final frame during yet another powerplay when Carter swatted his own rebound past Smith.
The Kings went 3-for-5 on the powerplay, while the Flames were 0-for-3 with the man advantage.
"Our powerplay's really not giving us any life and when your penalty kill leaks a little bit like it did tonight, it's tough," Gulutzan said.
