"We're very close friends, and we've been friends for a long time," she said of Foster.
"I'm really, really fond of him and I think he's an incredible person. I've known him since I was 21 years old, you know? he produced my first single. So he's been really good to me. People can say whatever they want."
McPhee and Foster were linked in May after they were spotted together in Malibu.
Speculation intensified after Foster's daughter Erin referred to Foster and McPhee as "my parents" in an Instagram post in September.
"So we were sitting there at the table, and she said, 'Do you wanna, like, do a thing?' And I was like, 'OK.' So I mean, we were in on it," the actress explained.
"She's so funny -- I mean, you saw what she wrote about 'my parents.' Truly, you think that's how she'd announce it?"
E! News reported that McPhee and Foster seemed "into each other" at a Lakers game Sunday. The pair were spotted laughing during the game, but kept the PDA to a minimum.
"They seemed to be having fun," a source said.
"They were chatting with the people in the seats next to them... Didn't see them kiss or hold hands but [they] certainly seemed like they were into each other."
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