Pakistan whitewashed the West Indies 3-0 with a convincing 136-run win in the third and final one-dayer here yesterday.
The series win lifted Pakistan one place to eighth in the current rankings and relegating the West Indies to ninth in the fight for a direct berth at the World Cup finals in three years' time.
Hosts England and the top seven teams in the one-day rankings on September 30 next year will get a direct place in the World Cup.
Ali said the win over West Indies was important in the quest for a World Cup place.
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"It was an important series and it's just the start of more challenges," said Ali.
"We have to keep this improvement with one year to go for the (World Cup 2019) deadline."
But Ali believes the confidence level of the players was high after the series win over the struggling West Indies.
"We have good players who have gelled well," said Ali, who singled out batsman Babar Azam for his three successive hundreds.
Azam scored 120, 123 and 117 in the three matches to become only the third Pakistani and eighth batsmen in all one-day cricket to hit three consecutive hundreds.
Ali credited new head coach Mickey Arthur with the improvements.
"Mickey has an important role," said Ali of the former South African and Australian coach who took over in May this year.
"It's a full team and the credit also goes to the selection committee, fielding coach Steve Rixon, physio Grant Luden and (batting coach) Grant Flower -- all have contributed a lot so it's a full team."
"We can challenge Australia as well because we have new players who are match winners.