Kroes' comments came at a commission press briefing ahead of Tuesday's planned reduction in roaming fees, which will now drop to €0.19 per minute for outgoing calls and €0.05 for incoming.
"This huge drop in roaming charges will make a big difference to all of us this summer," said the Dutch official, who was critical of the "out of date, old fashioned roaming rules on our internal market".
"The majority of Europeans want a 100 per cent end to roaming fees" - Neelie Kroes
Kroes, while supportive of the reductions, stressed that the price drop was "not enough", adding that she was "confident that before Christmas 2015 roaming will be gone forever".
The European parliament voted in April 2014 to remove roaming charges entirely, with the rule change set to take effect from 15 December, but the member states have yet to lend their approval.
"The fight continues," said Kroes, who underlined that "the commission has done its bit, the parliament has done its bit and now it is down to national governments".
Consumers have faced huge bills after using their mobile devices while travelling in other member states, and the commission estimates - based on data from the body of European regulators of electronic communications 12th benchmark report - that, since 2009, EU consumers have saved €9.6bn through reduced roaming charges.
"We have achieved further guarantees to maintain the openness of the internet by ensuring that users can run and provide applications and services of their choice" - Pilar Del Castillo Vera
Kroes praised the "annual effort by the EU to deliver a better deal for consumers", highlighting that, "In the US they offer free roaming to over 100 countries, including the EU, but European consumers do not enjoy the same support."
"People around the world are looking to the EU to deliver common sense," she added.
Rapporteur on the European single market for electronic communications Pilar Del Castillo Vera said, following MEPs' plenary vote in April, that "parliament wants to abolish retail roaming charges for voice, SMS and data by 15 December 2015".
"We have achieved further guarantees to maintain the openness of the internet by ensuring that users can run and provide applications and services of their choice as well as reinforcing the internet as a key driver of competitiveness, economic growth, jobs, social development and innovation", added the Spanish deputy.
"The fight continues," said Kroes, who added that, "The majority of Europeans want a 100 per cent end to roaming fees."