Giving evidence at Southwark Crown Court in London, the woman said she met the entertainer while on holiday in Malta in 1970.
Her boyfriend hurt his foot while swimming and Harris, now 84, came out of a bar and helped them find a doctor.
The woman then went back to thank the artist and he took her into a side room, offering to show the aspiring art student some of his work.
It is claimed he pinned her against a wall and gave her a “slobbery” kiss before touching her intimately.
Prosecutor Sasha Wass QC yesterday asked her, “Did he say anything?” to which she replied, “(He said) ‘I’m sorry’.”
The woman said she was “in shock, really, happy that was it. I thought I was going to be raped.”
Afterwards, the pair went back to the bar, where the woman told the court she had her photograph taken with Harris. She said the entertainer squeezed her arm “really tight” as the picture was taken, adding: “It was as if it was an apology.”
The alleged victim is not named on the indictment because the claimed incident happened abroad before such crimes could be prosecuted in the UK, but she has been called as a prosecution witness.
Harris is accused of 12 charges of indecent assault against four alleged victims between 1968 and 1986, all of which he denies.
He listened intently from the glass-walled dock, with wife Alwen and other family members including his niece and brother-in-law watching from the public gallery.
The court also heard from two other women who are prosecution witnesses and were flown from Australia and New Zealand to give evidence.
The first of the women told the jury of six men and six women that when she was 11, Harris told her that he wanted to be the first person to give her “a tongue kiss”.
She said she was at a family friend’s home in Australia in 1969 while she was off sick from school, and came downstairs in her pyjamas to find Harris, who had been polishing a piece of wood.
The woman said: “When I came down the stairs, he asked me how old I was, and he said, ‘Good, I want to be the first one to introduce you to a tongue kiss’.”
It is claimed that Harris got her in “a gentle hug” and kissed her, putting his tongue in her mouth.
She said: “It seemed like it lasted forever but it must have been very quick. I was quite repulsed by it. Absolutely repulsed.” Jurors were told that another woman was 16 or 17 and was working for a wine company at a party in New Zealand in 1970 when she met the entertainer.
She said that she and another member of staff had photographs taken with Harris and his friend, and he gave her his autograph.
At first he was “very friendly and very relaxed”, and was “being stupid”, posing for the pictures, she told the jury.
But Harris then asked her to dance, slid his hand on to her bottom and put it between her legs.
After the woman felt Harris’s hand between her legs, she said she pushed him away and left the venue. The woman told the jury she informed her mother about what had happened the next day.
In April last year after media reports that Harris had been questioned by police, she said she felt relieved and she told the court: “I thought, ‘They’ve finally got the b******’. It was all those years later but it was unbelievable, the relief I felt.”
The trial continues.