Revenue grew two per cent in the third quarter on an organic basis to €537m (£480.6m, $586.6m), against growth of 2.7 per cent in Q2 and 3.4 per cent in Q1. Organic growth across the first nine months was 2.7 per cent for Havas.
The company - which does not give figures for its PR business, which includes Havas PR and Maitland - described Europe as its "growth driver", with organic revenue up 7.7 per cent in Q3.
Havas cited the "very strong third quarter from the UK agencies, in spite of the macro-economic climate", while France, with organic growth of 2.9 per cent in Q3, "merits a special mention for a fine performance in both creative duties and media".
Growth across other European countries was 11.8 per cent in the third quarter, with "the biggest contributors" being Spain, Italy, Portugal and Belgium.
Havas reported a 1.2 per cent decline in organic revenue in North America, which it attributed partly to the one-off impact of client Draftkings being forced to halt a particular promotional activity. Despite this, Havas said Havas Health and Havas Chicago "continued their strong performance" and the firm said it expected the situation to improve in the fourth quarter due to new wins.
Organic revenue fell 6.3 per cent in Latin America in Q3, although Havas said the performance across the first nine months of the year was in line with 2015.
"There were contrasting performances: Brazil improving, Argentina dynamic and Mexico slipping but apparently stabilizing thanks to the development of certain major clients," the company said.
The Asia-Pacific and Africa region also saw a steep decline, with organic revenue down 7.1 per cent in Q3, although there was modest growth across the nine months (1.5 per cent). Havas cited a "significant slowdown" in China but pointed to "strong growth" in Australia.
Despite the positive growth in the UK, exchange rate fluctuations had a negative impact of €46.3m (£41.4, $50.6m) across the nine months, with the falling value of the pound cited as a reason, along with the declining value of currencies in Argentina, Mexico and Brazil.
Overall revenue grow was 3.8 per cent in the third quarter. Revenue across the nine months was €1.63bn (£1.45bn, $1.8bn), up 4.7 per cent, or +2.7 per cent on an organic basis.
Havas also confirmed it is due to open its next Havas Village in London in the first quarter of 2017, which is set to house more than 2,000 UK employees from different parts of the business
The company had earlier earmarked the end of 2016 for the opening of its latest 'Havas village' - a concept first operated by the company in France five years ago - this time in London, with the base serving as its European HQ.