The British prime minister said the variant, which has killed at least four people in the UK, could pose "a serious disruption" to removing restrictions in June.
The UK will take the next step to ease COVID-19 restrictions next week, Boris Johnson has confirmed, after concerns were raised over deaths resulting from the highly transmissible Indian variant.
The British prime minister said on Friday he didn't feel the need "on the present evidence" to delay the roadmap, which will allow for indoor gatherings from Monday.
"We're in a different position from the last time we faced a new variant," he told a Downing Street press conference, referring to the Kent modification that ripped through the country before Christmas. "There is no evidence increased cases are translating into unmanageable threats."
Johnson did, however, warn that the B.1.617 (India) variant could pose "a serious disruption" to further progress - especially in regards to June 21, when much of the UK is hoping restrictions will be dropped completely.
"The truth is at this stage we can't say for certain," Johnson said. "As things stand, the numbers of infections even with the new variant remain low overall across the country...
"We've just got to wait and see... We won't rule anything out."
Johnson's urge for caution comes after four people were confirmed to have died with B.1.617 in the UK, along with a spike in infections in areas such as Bolton and Blackburn. However, he said, there was "no evidence" of increased cases translating into unmanageable threats.
Another 2,193 cases of COVID-19 were recorded in the UK on Friday - far below the tens of thousands of cases seen every day in the weeks after Christmas. There were also another 17 deaths.
The World Health Organisation (WHO) declared B.1.617 as a variant of global concern earlier this week, due to early studies suggesting higher transmissibility.
It has already taken a firm hold of India, which has seen 24 million infections and has recorded three consecutive days of more than 4,000 deaths.
As a result, Johnson announced a strategy of surge vaccinations for certain age groups and the clinically vulnerable, adding that there is "no evidence" to suggest inoculations would be any less effective.