With this, there are now three MPs of Indian-origin in Prime Minister Boris Johnson's Cabinet.
Javid resigned during a cabinet reshuffle because he refused to accept Johnson's order to sack his advisers, the BBC quoted sources as saying.
Asked about Mr Johnson's declaration in the register, the spokesman said: "I believe it is a mistake".
Javid had been widely expected to keep his job as Johnson fired some Cabinet members and promoted more junior ministers to top jobs.
Javid, who became Chancellor of the Exchequer when Johnson succeeded Theresa May as prime minister in July, had been due to deliver his first budget in less than a month - a crucial staging post for the government in the wake of the country's departure from the European Union last month.
Downing Street aides had previously played down suggestions, based on Johnson's senior adviser Dominic Cummings' well-publicised desire to see a radical reorganisation of government, that there would be major changes. That involves ambitious infrastructure plans, including a 100 billion-pound ($130 billion) high-speed railway connecting London to central and northern England. It was clear that loyalty mattered to Johnson to be able to deliver his agenda and meet the promises he made in the run-up to the December 12 election, in which he won a large majority.
So far, the two sides are far apart in their demands.
Several high-profile women in Johnson's government, including Business Secretary Andrea Leadsom and Housing Minister Esther McVey, were fired.
Anne-Marie Trevelyan was promoted to minister for global development, while other big departments - such as foreign, home affairs, trade and health - kept their ministers.
The British province had no government since Sinn Fein and the Democratic Unionist Party (DUP) fell out in January 2017 over a renewable energy scandal.
Brandon Lewis, a former security minister, was named to replace him.
Ultra-loyal Alok Sharma, a former minister for worldwide development, was appointed as the new minister for business and also the head of the COP26 climate change summit in Scotland in November, due to be attended by world leaders.
Johnson also named former aid minister Alok Sharma as the new minister in charge of the COP 26 United Nations climate summit, which is being held in Glasgow in November.
"It has been a real privilege to serve in government for the last six years".
Meanwhile, Alok Sharma, the former secretary of state for global development has been elevated to the role of the secretary of state for business, energy and industrial strategy.