The Beatle and his wife Nancy Shevell were among the mourners to lay flowers at the vigil set up outside the hotel where Houston died on Saturday (February 11).
As McCartney paid his respects to the late 'Run To You' singer, a photographer asked him to comment on his Grammy Awards performance.
"This is about Whitney, not me," McCartney replied, according to TMZ.
The Jackson family also paid tribute to Houston on Monday, with Janet Jackson, Randy Jackson and Jermaine Jackson offering personal remembrances on their Twitter accounts.
Jermaine reflected on Houston's passing by writing: "The right words fail me to sum up the sense of loss following the passing of Whitney... a wonderful woman, a true heart, and an immense artist."
Jennifer Lopez also praised Houston's influence during an appearance on The Tonight Show with Jay Leno.
The American Idol judge described Houston as a "voice of our time and our generation".
More Whitney Houston Coverage:
> Whitney Houston 1963-2012: Reactions
> Whitney Houston 1963-2012: Obituary
> Whitney Houston: A life in pictures
> Whitney Houston: Greatest musical achievements - pictures
> What is Whitney Houston's best song? Poll
> Clive Davis dedicates pre-Grammy party to Whitney Houston
> Whitney Houston to dominate singles, album charts next week
> Bobby Brown: "I love you, Whitney"
Watch Whitney Houston's 'Run To You' music video below: