Andrew Mondia was just three days into his role as Father Christmas in the Grotto at Selfridges when he was fired after the grandmother complained that he had offended her.
Canadian-born actor Mr Mondia, 32, said that hadn’t been his intention and he treated all visitors the same.
He said: 'I can understand how that may have been seen as disrespectful but Christmas is for everyone.
'I’ve had all ages sit on my lap, from elderly ladies, younger women in their twenties and thirties and even some men, so I ask everyone. If they say no, then I don’t pursue it.'
He added: 'I was just being my innocent usual self. I was shocked when they told me. I couldn't believe I've been sacked for being too friendly.'
The woman complained to Mr Mondia’s supervisors on Monday after she visited the Oxford Street store with her family.
A spokeswoman for Selfridges said all Santas in the team were told during their induction that no one should sit on their lap and Mr Mondia 'didn’t behave in line with his training'.
The company said it is made clear to potential Santas during their training that no one should sit on Santa's lap and Santas must certainly not 'promote or proactively seek' anyone to do so.
Mondia had also been warned by his helper elf several times that he should not ask clients to sit on his knee, they said. The 32-year-old - who said his elf had given him no cause to worry about his behaviour - was finally approached by a supervisor at the end of the day and told that his services would no longer be needed.
A spokesman for Selfridges said: 'It's vital that everyone bringing children to see Santa can be absolutely confident that the visit will be a happy one. Unfortunately, this particular Santa didn't behave in line with his training or the standards we've set so we acted swiftly and asked him to leave.'
Mondia insisted that during his one-day training, which was 'a bit rushed', potential Santas were warned that if children wanted to sit on their knees they must be placed there by their parents, but at no point were told that the action was forbidden. 'I was just being my innocent usual self. I was shocked when they told me – I couldn't believe I've been sacked for being too friendly,' he said.
Mondia - who at other points in his career has posed as a box of Nesquik and a Blackberry pearl mobile phone - was set to work six days a week, at £9.75 an hour over the festive period, which would have earned him around £2,500, he said.
He said: 'I'm not sure what I'll do now. I'm looking for other jobs but it's going to ruin my Christmas because I'm not going to have any money and I wanted to carry on having fun as Santa Claus. It's disappointing, but I've learnt that, even as Santa Claus, you can't please everyone all the time.'


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