He told USMagazine.com at the Jingle Ball in Madison Square Garden in New York: "I'm happy they're good friends and she's a really lovely girl."
The British boyband star also revealed he has spent a lot of time with Taylor recently as things heat up between her and Harry, who is reportedly planning to show his affections by having a ring made for her 23rd birthday next Thursday.
A source previously revealed: "Harry's been on the phone to leading Los Angeles jeweler Robert Procop, who designed Angelina Jolie's engagement ring.
"He's been asking advice on what pieces can be made, or what are already available that would suit Taylor.
"Harry doesn't want anything too over the top or too ostentatious. But he's happy to splash the cash on a nice ring, not an engagement ring or anything silly like that. He's looking for something traditional."
The singer has also been talking to another top jeweler, Tiffany's, in New York.