James Cowles, who heads up Citi's operations in Europe, Africa and the Middle East, told Les Echos the bank was trying to keep as many options open as possible.
He said the recent labour market reforms adopted by the government of President Emmanuel Macron made France a more attractive place to do business, and Citigroup was interested in adding several activities to its banking operations in Paris.
Competition has heated up in recent months between cities hoping to lure business from London once Britain leaves the European Union in March 2019.
The terms of Britain's exit from the bloc are still unclear, but many financial firms are planning for a possible move of their EU operations into the bloc.
Frankfurt, which is home to the European Central Bank, is widely seen as being in the lead to attract London financial exiles.
In July, Citigroup informed its staff it was converting a German subsidiary into an investment firm to transfer the headquarters of its EU brokerage activities there.
It said Frankfurt was the first choice given the city's infrastructure and the staff it already had in place there.
However Citigroup also already planned to boost its presence in other cities that have been seeking Brexit business, including Paris, Amsterdam, Dublin and Luxembourg.
Cowles noted that Citigroup had already moved its European banking operations to Dublin in 2016, before the Brexit vote.
Cowles told Les Echos that London would still remain Citi's operations across the Europe, Africa and Middle East region. He said 6,000 of the the bank's 19,000 Europe-based employees are in London.
He said Citigroup believes Brexit would affect no more than 100 to 200 jobs.