According to Mr Johnson's figures, the number of Indians applying to study in the UK dropped nine per cent this year and is forecast to fall a further 25 per cent next year. Of the 110,000 foreign students in London alone, 9,000 are from India, where Mr Johnson is spending this week trying to build business links with the capital.
In interviews ahead of a speech to prospective students at Amity University, the equivalent of Oxford or Cambridge, Mr Johnson said he was worried the "mood music" from Whitehall was putting the very best off applying.
He said: "We are going to set up with Government an Education Exports Commission to look at the issue to make sure we get the right message across so that if the Government decides to make changes to the visa regime it doesn't do damage to a sector in which London is so strong and it is so valuable.
"The vast majority of Indian students do get a visa, 75% of them get one pretty much straight off. It's more of a perception at the moment.
During Boris Johnson's visit to Delhi he handed over the London 2012 Olympic cauldron petals to Indian Olympians (PA)
"The policy on visas is, in my view, sending out the wrong signal. There are so many stipulations that we are starting to lose business to Australia, America and Canada.
"As I have written several times to the Home Secretary, we need to see a strong statement of welcome to make sure that the visa system is not a deterrent to international students.
"The extra stipulations such as the need to have a salary of up to a certain amount before you are allowed to stay on mean we need to be very careful that we are not doing stuff that actively deters foreign students and at the moment the policy seems to put people off. Why are we doing this? We shouldn't be losing this market."
He added: "It's very important for our higher education economy that you have foreign students who contribute £2.5 billion a year in fees. Now that helps to subsidise the rest of the university sector – helps to pay for everybody else's education.
"It's a great idea to have a London that is open to that kind of business. I am saying to Government 'Don't do things that is going to cause unnecessary alarm and prejudice against the UK'."