(Reuters) - Snap said on Tuesday it will not issue a second-quarter financial forecast citing economic uncertainty, as U.S. tariffs threaten to disrupt the global economy and digital advertising budgets, sending its shares down 13% in extended trading.

The Snapchat parent faced challenges at the start of the current quarter, even as it continued to diversify both its advertiser base with small- and medium-sized businesses and its revenue sources with the growth of its subscription service.

Snapchat+ subscribers rose 59% to 15 million in the first quarter.

But economic uncertainty could trigger an ad spending shift to bigger rivals such as Facebook and Instagram owner Meta due to their massive user base, analysts have said.

Snap's results come after Google's ad revenue growth beat analysts' predictions for the first quarter.

The company is focusing on direct response ads that are designed to prompt specific actions like app downloads or website visits, amid weakness in brand awareness ads.

Direct response ad revenue reached 75% of Snap's total ad revenue contribution for the first time in the quarter ended March 31.

Total active advertisers grew 60% from a year earlier in the first quarter, driven partly by the company's focus on small- and medium-sized businesses.

"While it's clear that Snap has had success courting small businesses, it's far from the only social platform chasing their ad dollars, making it more difficult for the company to truly make its mark in this realm," eMarketer analyst Minda Smiley said.

Revenue rose 14% to $1.36 billion, slightly beating analysts' average estimate of $1.35 billion, according to data compiled by LSEG.

Adjusted earnings before interest, taxes, depreciation, and amortization of $108.4 million in the quarter exceeded estimates of $64.7 million.

Daily active users of Snapchat increased by 9% to 460 million, beating estimates of 458.3 million.

The company said its monthly active users reached 900 million, on track to achieve its target of 1 billion.

Snap trimmed its full-year forecast for adjusted operating expenses to between $2.65 billion and $2.70 billion, compared with its prior expectations of $2.70 billion to $2.75 billion.