The article, which Polanski says is libelous, said the director tried to seduce a woman while on his way to the funeral of his murdered wife, Sharon Tate.
"This was the worst thing ever written about me. It's absolutely not true," Polanski, 71, told the London jury of nine men and three women, the BBC reported.
Polanski admitted cheating on Tate during their marriage, but said the charge made by the Conde Naste magazine "dishonors my memory of Sharon," who was killed by followers of Charles Manson in 1969.
Polanski is testifying via a video hookup because Britain could extradite him to the United States, where he was convicted of having sex with a 13-year-old girl in 1977. He has been living in exile ever since.